Just putting in my 2 cents worth.

My group in mostly level 78 gear from instances

resto druid
balance druid
elemental shaman
aff warlock
prot pali

basically spent most of my time gearing up my prot pali (made sure he was over defense minimum) and my resto druid. Most of my other chars dont have any enchants or gems

When I started doing herioc utgarde keep highest dps was my prot pali just barely breaking over 1200 dps, averaged over the whole run using (using recount)
My other chars barely broke 1k dps.

After spending about a week doing utagarde keep, some boss in Drak'Tharon Keep and take my char one at a time to the target dummy to improve there dps macro
My prot pali still only doing about 1200 dps but all my other chars are on average doing over 1300 dps with the warlock having the highest variability depending on whether or its a boss or just trash mobs

Now I just gotta work on getting my guys "to hit" higher and figure out different macro from trash mobs and bosses.