my first 5 box group was a mixed group, pal,dru,mage,sham, lvl 80 lock or DK to help on the group quests. I took them to lvl 74 before I read about an all PAL group.

I leveled the 5 pals to 55 then swapped out one for a same lvl DK, and leveled them up to 80 as DK+4 rets. That was very fun to do, and the rets provided ok healing but never could get the group healing down right. If I fought a mob that did AOEs I was usualy done for unless I burned them down quick.

I have just started a 5 feral/boomkin troll druid group that leveled to 51, then dropped one out and am boosting with a 85 lock.

Ultimately it is play what you like, as you are the one that has to play it.

P.