While true, that iPod Touch is just SOOOO much more portable. And I'm thinking about getting one of those wifi hot spot devices. Supposedly, that's faster than wifi since it foes all 3G/4G on the tech side.
Don't get me wrong- I'll find a good use for my iPad...Digitech's IPB-10 is looking pretty good.
All I know is, if when both devices are sitting next to me, I use the iPad. But I don't take that with me everywhere (being bulky and I have a manly philosophy that all the stuff I need should fit in my pockets so my hands are free)
As for faster than wifi, the oldest wifi is 802.11a. It ran at 11Mbps.
According to this cnn article from last year, the carriers 4g speed was 12Mbps
Every wifi hub on the planet is running 802.11b or better, so you're wifi chip is going to deliver better than what cellular dataplans can deliver.
This is why I think its funny when folks ponder buying 802.11n hubs and paying extra money for faster internet speed. The oldest wifi hubs are faster than the speed most people get from their ISP. (note, I just got bumped from 6Mps to 12Mbps with U-Verse).
There are other advantages to the newer faster hubs (usually better range, go through walls, security, energy use). But speed itself, not quite what people think.
You may be better off sticking to wifi, asuming you are almost always in a wifi area (like courthouses, offices, etc). It's certainly cheaper if you can.