Have guilds in WoW grown bigger?

One of the really nice things of me rejoining World of Warcraft was getting tells from people that remembered me, and rejoining a more casual guild I have been part of in the past before playing in a raiding guild for some months. Although I am not principally I friend of guild hopping, I obviously feel more at home in a casual raiding guild (doing ok in Karazhan, probably just right for Zul'Aman) than in the hardcore raiding guild I left (where I would have problems catching up to them, as they are already in Tempest Keep). But one thing I noticed while looking at guilds was that apparently there are now less of them, and the surviving guilds have more members.

So I was playing pen & paper roleplaying last night, and as always WoW was discussed as well, as I had turned them all into WoW players in early 2005. (I'm a bad influence.) And one guy had this interesting theory about smaller, casual raiding guilds: Guilds are regularly losing members, because they either quit WoW totally, or just quit the guild to join another one. And more often than not the people who quit are at the better equipped end of a guild. People who are already geared up well, but feel that their guild isn't advancing fast enough for them to get to the next gear level are more likely to quit or change guild. People less well equipped often get a decent number of epics in their first raids because everyone else already has them, and are thus more likely to stay. So now what happens if you have a relatively small guild, with relatively few raids per week? The number of epics you lose from people leaving becomes large compared to the number of epics you earn every week from raiding. Thus small, casual raiding guilds can become stuck at some point of the raiding process, because their better equipped people don't stay around long enough to get everybody equipped for the next level of the raiding circuit. Ultimately the smaller guild totally disbands and people join larger guilds with a better raiding progress. Guilds that don't paddle hard enough simply sink. Thus the average number of players in a guild and the average number of raids guilds do is going up.

How does it look on your server. Did you observer guild consolidation, with less guilds being around, but having more members?