Yesterday there were a series of very interesting posts by Carl at Backstage Pass: A DM's Secrets. The basic gist is that Carl and Carter of The Lands of Ara played a 4E game. Carter didn't enjoy the experience, but Carl contends that the fault is not so much in the way his game was run, but in Carter's lack of interest in digesting 4E rules.
Carl contends that with sufficient 'mastery' of a game system, then any group can play any game "old school" or "new school" style. System matters, but only so much that everyone playing should know that system.
Now I agree that any group can play just about any RPG in just about any style. But I'm not sure that I agree that this is as easy as Carl thinks it is. Sometimes, I feel, the system encourages one playstyle over another. And it's not simply linked to a rules heavy/rules light dichotomy. Or a detailed/simple character generation system.
I feel that the system's reward system is also a big factor. A system that rewards teamwork and creative thinking when tackling puzzles will naturally play differently than a system that rewards success in combat by any means, fair or foul. A system that rewards repeated skill use regardless of context will play differently than a system that rewards you for completing story goals.
Now, any DM and group of players can play against type, and do it successfully, if, as Carl contends, everyone knows the system well enough. But in my eyes, getting that level of system mastery is a lot easier with something like BX/BECMI D&D than it is with 3E/4E D&D. (AD&D is somewhere in the middle.)
Anyway, I think this is an important discussion, so I wanted to let others know it's going on.