OK, I just want to preface everything with the disclaimer that I know squat about specifics regarding EN World.

Desert Gled has a few good questions and I think they should be discussed. I typed up a huge reply yesterday and then lost it when I had my user ID cache get hosed. (Just for the record, that is nothing on EN World's side. That was me at work doing other things.) So now I am doing what I should have done yesterday (and do for many of my longer posts), I am typing it up in a text editor and will copy/paste when I am done.
Desert Gled,
First of all, my apologies on the insufficient answer yesterday. All of us know that EN World uses a lot of bandwidth and I should have included that in my earlier post as a consideration. I do believe a dedicated server, leased monthly, is a strong contender versus a co-located server. I am not convinced it makes better sense, but I do not know since I can only speculate on several things. But it is good discourse and if nothing else, it does help demonstrate all the factors the server team has to take into consideration. They are doing a great job and will continue to do so, I am sure.
I will continue to use Cedant as a baseline because I am passingly familiar with their product offerings. Note, I have never used Cedant, but I know their name and have looked at them as a possible solution for a couple of different projects over the years. Also, I am in my "work mode" so I apologize in advance if any of this comes across as brusque, it isn't intended that way.
A dedicated server option certainly has some robust servers available. You can always make a server that is a little faster and a little better, but the dedicated server options are certainly good performers. On a purely hardware basis, it is difficult to argue against them. Since they are hosted, the ISP will have replacement hardware available. The servers will likely be on an upgrade schedule that is part of the monthly cost, etc. These are some fairly compelling reasons to consider a dedicated server at an ISP.
Basic hardware & OS troubleshooting will also be covered in the monthly fee. Especially since all the systems will be baselined to be the same. Places like that do everything to keep costs down by standardization. So, their server builds will try to use identical hardware with an identical configuration on top of that. Trust me, this _really_ helps keep maintenance, troubleshooting and repair as easy as possible. It is one of the things I strive to achieve with the servers I maintain.
This is all good stuff, but it does have drawbacks. For a site like EN World, there are performance optimizations that can be achieved by tweaking the kernel and applications for your specific needs. I am not sure if the server team has any of those planned, but in a dedicated environment, you will not be able to tweak things the same way. This is particularly notable with some of the PHP caching software because I am not sure we would be able to install it on a dedicated server, nor would there be any assurance that it would still be installed when the server is moved to a different piece of hardware. Because some of the performance optimizations could be significant, this might be a big concern.
Another concern is that a dedicated server does not give you direct access to the hardware itself. This can make troubleshooting difficult. If you need to see the console, or do anything from the console, Cedant does give you a small window of time with one of their techs. But if the problem cannot be quickly & easily solved, then you need to restore from backup, or pay for higher level troubleshooting/support. At $150/hour, this can add up pretty quickly. It is also notable that Cedant lists this rate for software/OS troubleshooting, customizations and patches. So, it might be possible to tweak the kernel and the applications, but it may require paying for the time of a tech to do that for you. This devours the $3000 buffer that might be realized by not purchasing a dedicated server.
There are several upgrades and value-added-services that are offered that can make the dedicated server a little more robust. OS upgrades, RAM upgrades, Hard disk upgrades, increased resiliancy, as well as backup options and resetting the server to presale conditions are all things that can be purchased. These are great services, however they also tack on more costs to the setup & monthly fees. It doesn't take long before before this starts adding an extra $40, $50, etc to the monthly cost.
There is also the bandwidth concern. I have no idea on the needs for bandwidth, though I _think_ I recall hearing that EN World would saturate a T1 connection. Keep that in mind a little further down and let's look at average bandwidth consumption. For just a moment, let's assume that EN World consumes an average of 1 Mb/minute. That seems a bit conservative, but it is an easy number to work with. 60 Mb/hour, 1440 Mb/day, 43,200 Mb/30 day month. 43 Gb/month easily fits in most of the plans. As I said, I think that number is conservative, probably grossly so given that we have 600-1100 users online most of the time. So, we just need to adjust for real numbers if the server team wishes to make those available.
Unfortunately, that is not the only consideration. Bandwidth at the moment is another issue. During peak times, EN World needs more bandwidth available than the average. So, let's take a look at this from a different angle. Co-location.
Cedant offers co-location at $75/rack unit/month. So, a 1U server would be $75, a 2U server (or 2 1U servers) would be $150, etc. Then you pay for bandwidth.
We know EN World's costs are currently ~$400/month. Piratecat has also stated that the hosting costs will go up by $50-$100/month. Let us take a guess and say that Cyberstreet charges $50/rack unit/month. It is just a guess, but it fits the range that Piratecat mentions if the server team hasn't made a decision of a 1U or 2U second server. Let us also assume that EN World also has a 1U server currently. These assumptions would put current costs at $50 for co-location + $350 in bandwidth. Ouch!
Let's look back at Cedant's offerings. Cedant offers a T1 connection at $299/month. If Cyberstreet's rates are roughly the same, it would seem that EN World has at least a T1 connection. However, I think EN World is getting a better deal than that from Cyberstreet. Though, I only base that on a vague recollection that EN World can saturate a T1, and shaky guesses on how current expenses break out. If I had to guess, and I have to without any other details, EN World is probably getting a good deal on an Ethernet connection that allows high burst rates and very good sustainable bandwidth.
I am not privy to the details of Desert Gled's conversation with aplus.net, but it is important to establish that EN World needs sustainable bandwidth for normal use + enough bandwidth for peak periods. Just because a given machine might have a high speed interface does not mean the ISP is going to allow the server to use all of that potential bandwidth. Bandwidth throttling on routers will be used to assure that each customer receives the bandwidth they were promised and paid for.
As an example, where I work we have an 8Mb internet connection that is growable up to 1Gb. Our LEC throttles the connection so we don't use more than 8Mb. I can also choose to throttle the bandwidth on our router to only provide a certain amount of bandwidth to our servers. In this case, I might throttle traffic to our SMTP and HTTP servers and leave a guaranteed level of bandwidth for the rest of our systems. It is important to understand exactly how much bandwidth would be offered to a dedicated server at any given peak moment. It would be possible to see site performance plummet during peak hours because the bandwidth was saturated.
Bandwidth is a big concern and the wrong bandwidth solution could eliminate most of the benefit of a faster server.
Back to the dedicated server vs co-located server debate. There is another issue to consider: Ownership of the server. With a co-located server, you have access to the physical hardware and if you need/want to relocate, you pick up the server and leave. With a dedicated server, you cannot do this. If EN World decided to move to a new host, the data and configration would need to be dumped to media, or transferred via the internet. We know the database is in excess of 1Gb right now. Perhaps that could be compressed far enough to be burned to CD, or maybe the files could be moved to a portable hard drive (at $150/hour), or maybe the files could be transferred, but this is a different level of ownership and complication.
It is an interesting assessment overall. I think it really helps point out the issues that the server team has to consider. A dedicated server, as opposed to a co-located server, is a compelling option. But there are many issues that might make it less effective. In the end, these are issues that the server team has to consider and assess. There are likely issues that I haven't even touched on yet.
My word this has become long. Look at the way I spew when I get to thinking. Stop me now! All of us want to see a robust, speedy, stable EN World community for a long time to come. I am sure the server team will make the best decision they can for EN World.