http://eu.battle.net/wow/en/forum/topic/1528723239
The definitive topic on 10 versus 25 man and something that anyone who thought 10 was easier (pre-nerf) should read to see how wrong they are.
I don't really have a dog in this fight so to speak but I think the issue at heart is essentially pride, 25 man used to be the more difficult, far and away and now the difference is marginal with a slightly higher difficulty leaning more towards 10 man, everyone just needs to take some deep breaths, calm down and raid whatever they like more.