I think the Cata raiding system is good for small guilds like mine. My guild used to have 10-15 good players, and the rest were so-so. We could do regular 25man, but no way we could carry the rest and pull of hard modes. Since ICC, I've only been doing 10man. 25 man is too much of a hassle with loot distribution, attendence, class composition, etc etc etc. Then again, I'm not a top-tier hardcore raider.