Actually, I would have to say that I don't find it that difficult. Of course, it helps that the game that I am playing a character in is actually 3.0 D&D, which is quite different from the 2E that I use in the games that I DM. Actually, I am rather enjoying not having to deal with all the stuff that the DM does when running a game, for the first time since I started DMing. With playing a different version of the game than I am used to, I actually find myself having to ask questions about things that I am not quite sure of.
If asked, I will give them my take on that particular situation. Like Grim and Inquisitor have said as well, I would not want to turn into a rules lawyer. I figure that each DM is going to do their own thing to make the game their own. Besides, you can always manage to steal.... er borrow an idea from another DM/GM, whose game you're playing in.