Hypothetical Scenario: You're thinking about joining a 15 hour / week raid group with the goal of clearing Naxxramas a month or two after P6 drops. You look at the roster and say, "Nope, that's too many hybrids." How many did you see?
(We'll just say everyone has perfect attendance, so raid size = 40. We'll also assume that everyone is friendly and equally skilled, however, optimal specs might get poached more but too many sub-optimal specs might hurt future recruitment.)
Edit: I noticed the counts were wrong right as I hit post, and polls can't be edited. It should be:
0-2
3-4
5-6
7-8
9-10
11-12
13-14
15-20
21-25
26+
Off-specs also count as hybrids, for example Arcane mages, Survival Hunters, Arms Warriors, anyone that isn't one of these 9 specs:
Prot Warrior
Fury Warrior
Holy Pally
Resto Shaman
Marksman (?) Hunter
Combat Swords (or daggers?) Rogue
Resto Druid
0/30/21 or whatever the optimal Warlock spec is
Fire Mage
Holy Priest
Based on what I've read I think I'd go with 5 or 6. I could handle a ret paladin, a feral druid, a boomkin, two shadow or disc priests, and maybe the RL's girlfriend that just has to play Arms warrior. But more than 6 I'd probably start looking at server transfers...