uhh... I haven't been here a while but... I've been reading these posts and I think I need to say this...
Look. While everyone's on the subject, and I'm sorry if this sounds mean I'm not out to frustrate people but I think this should be said. You're gonna have problems. You'll ALWAYS have problems. It's like stores will always get robbed, currency will always be counterfeited, politicians will always be idiots and big-name companies will turn innocent dreams into filthy cash-cows. Sure you can up the surveillance, sure you can you can make copying money illegal but does it solve the problem? No. Sometimes, solutions barely push it back. You're always gonna have morons who don't know what Co-op games really are, you'll always have terrible RPers and even worse hangout areas and you'll always have god-awful mods and WADs that make your eyes bleed when you look at them. There is no permanent solution to everything and I think that, if the Admins would recognize this, they can save themselves alot of time trying to fix a problem that's always been here and always will be here. The problem of getting people to listen. Look, people are always gonna break the rules. Ask any cop who's worked for a few years, ask any AA consular, doctor, therapist, or just any honest person who's worked for a living. If people like the game, they will respect the game and maybe not follow every rule to the letter like not RP but set up a private server as a compromise and if people want the game to stay alive then they will report the people who break the rules. The best thing any Admin can do is enforce the rules by catching people on first report. It might seem like an endless problem and it might seem like there could be a better solution but you really are just creating more problems and even though it might be as efficient as we'd all like it to be, good ol' fashion law enforcement keeps things lively and simple.
And so what if people host private matches where they RP with a couple poor sobs that are simply looking to make their own little fun out of a game they love? The people who suck will have their little isolated world and the awesome-rockers of the RP world will have their own little isolated epic fun. I get that people think Sonic is all one straightforward level and, yes, it started out that way but the attraction to me about SRB2 is that it's more than 'go as fast as you can to beat the timer' and such. It's taken gaming to the next level for 'older' players. It's world has become more detailed and intricate for those of us who preferred games like Sonic Adventure for it's RPG-like playability and it's level design. The game has made Sonic evolve in such a way that it brings it to that next level so why shouldn't the players add their little something even if it's just acting out their character or getting really into Match games with crazy battle cries? If anything, I'd think the creator and Admins would endorse a little extra fun at no one's expense if it's kept isolated.
Blue Warrior, I think I agree with your solutions the most. Having multiple Master Servers is a good thing for different people. Variety often solves many problems.