You might want to take a look at the first page. The one in which Ellay posted a picture of his 4 shammies in a ZA run.

And as far as it being accepted in most guilds I highly doubt it. People are greedy and if one person get to take up half of a raid people are going to complain. Sure you have to play all of the characters but people will see it as one person getting five times the loot.