Why not just tell him? I don't know how well you know this person, but you risk him being miffed at you if he finds out that you knew it could be done and never told him. System mastery is great for those who have the time and analytical skills to achieve it, but that's no reason to penalize the others by deliberately withholding information.
I seem to be getting told off in this thread for things that I should or should not do- is it me or are people very judgemental today, and quick to condemn.
Why have I not told him- because our game is excellent, great- it is by far the best D&D I have ever played, and I'm mid-40's and started with the first red box. That said if there's a problem with the Core modules that we're playing through (RAW) at the moment it's that my players (as it stands) are handing me my backside- I am therefore having to scale up encounters (as above) just to keep them challenged. Given them another boost and, well I'd have to rescale again. We have as a group talked about this- the consensus is- 'whatever you think'
And for context, as above, the players are not D&D/RPG-centric, I would say for four of the five that the only time they talk about D&D is in our sessions, they have families, businesses, children etc. which demand their time- they don't own miniatures, books et al.
They do appreciate four to five hours out once a week in which they drink beer/wine and act out, Iain knows the rules that apply to the characters he's created and played. I am certain that Iain doesn't know quite how Rituals work, he has likewise never read any of the rituals (save once- when he decided he wanted a few (he'd found a scroll with a some on and looked into it- for less than an hour)). Iain doesn't know the difference between a Demon/Devil/Elemental/Immortal et al- someone (Becky or James (or me)) usually has to remind him, and its not that he's not bright- he's got at least one degree, I know he used to be a lecturer and is now a very (I think) successful businessman.
Imagine players that are unlike the people here at ENWorld, who play the game (mostly) for kicks, who don't learn rules, or obsess, their characters have no backstories, they don't go looking for images of them. Iain I would bet my house has probably not read more than ten pages of the Players Handbook, actually... I'll phone Iain.
I'm back- Iain has read approx. ten pages of the PH- usually the first two pages about the character class, although I had to explain to him which one the PH is- as stated earlier, one of my players has the PH the others have nada. When he got to Paragon Level he just asked James (who has the PH) what should he take, and its not that he's not interested- he's never missed a session and he has the most going on in his life. He just doesn't... obsess.
The players seem to like our game as much as I do, Iain (the Wizard) sneaks out of the house to get to the games, and gets in trouble for it later... the rules are, well I need to know them but the players are much less bothered.
I probably will tell him, but not for a bit- imagine you've just got things sorted and then something comes along that will change the dynamic again and cause you to head back to the drawing board etc.
In fact I will tell him after we've finished P1, and try it out on P2, if it's too overpowered then I'll house-rule it away...
It's just a game, the rules are great, but if they unbalance things, or else change for the worse what is a great game then they're gone.
As to Iain being miffed, again I'd bet my house, it's just a game- a great game that six people are enjoying immensely, we've even started up a second party with the assorted children of some of the players- they love it too, now they read the rules- the adults- information overload, if they need to know they ask, I promise you I'm not doing this out of spite.
I asked the question here (in the other thread mentioned) because I didn't know the answer- now I have all of the 4e WOTC hardbacks, every WOTC (and third party) module, and lots and lots of other stuff besides- I'd say 3,000+ miniatures, every floorplan set (and lots of the Paizo battlemaps)- I'm the obsessive, and here's the thing- I've never read one of the books all the way through (except the modules).
I just play the game, and ask here when I'm not sure or can't find the answers.
Cheers Goonalan.