Xorn: For that particular setup I would definitely go with a shaman healer. It just brings so much to the table.

Edit: I gotta warn you...you're gonna have a hard time in Heroics. I'd think about swapping the lock for a mage just for that one sheep alone, not to talk about the free food/water and portal travel.

I know for instance a pally+4 shadowpriest setup can look tempting, but it's just not practical in the end.