The best way to gauge is to ask you this: how many Rohan Gold people actually stepped foot in Naxx? Not even fought a boss but actually zoned into the instance before BC came out. And now that getting AD rep is much harder due to the level/reputation gap and how many can even try to get into Naxx? When Burning Crusade came out and raids dropped in size, lots of the bigger guilds took a hit where the best geared and core members reformed into a 25 man system.