Bankofkobzz
Legend
what i am going to say is probably totally irrelevant but my guild is a 70 raiding guild with zero WOTLK enchants and gems, and we literally 5 man'd karazhan and 8-man'd magtheridon. they shouldn't have much problems even with the gear... BTW we didn't outgear the content at all...
with the new talents and major class buffs, the dps is around 3x as it was back in the day. even with no tier gear I doubt you will actually need 40 people.
however i'm only sharing my experience at 70, might be different at 60, though i doubt it...
The problem with making strict rules like this is that it would really only attract raiders because you would have to earn two gear sets, one for pvp, one for pve. And with many pieces BiS for both this causes much frustration and ultimately would turn some people away from the guild. And as we all know, with 60/70/80 raiding guilds having quantity is extremely important to keep activity up.