Though i personally raid 25 man. I have to agree with a few posters. 11/14 Heroic at least in my opinion is not hard at all but once you get to siege/klaxxi/garrosh. Expect a minimum of 200+ wipes each boss. Even the top world guilds have well over 200+ Wipes on each boss. Best of luck to all you guys on your quest to get your mounts.
There are also threads on here strat issue for pretty much all bosses you can check out.