One of the reasons I'm asking this is because we have a few off-spec people in our raid: a Bear Tank, a Cat, and a Moonkin. While I don't doubt the abilities of the players in question (the Bear has tanked the Twin Emps successfully, amongst many other raid bosses), I do doubt the classes, specced that way, and the gear.
It's easier for a Cat to get aggro; the Moonkin doesn't seem to do anywhere near as much damage as the Mages (but it does bring about +3% damage for 4 others), and the Bear often dies first on Huhuran. And I bet we're the only raid out there that lets Moonkins roll on
Bracers of Arcane Accuracy together with Mages and Locks, because there is no viable alternative in Leather.
Hence, the question how much we are hampering ourselves through this. We are not a cutting edge guild; we usually have server second/third/fourth kills of new stuff. Therefore I think we view the world a bit differently than the guilds who are competing for world first kills. So, I was curious about what the other guilds out there thought about this.