My mixed groups are warrior, priest, hunter, warlock. My pally main goes with them and has no problems. Melee isnt so bad unless you have casters or ranged that will run AWAY from you. Then you have to reposition and try to get them to not run again.

My 5 shammies are melee/resto. I haven't had any problems with them at all until BRD. 5 lvl 52 elites attacking my lvl 56 guys and they run around while ranging/casting on me. The casters also have 2 schools, so you can shock them, but they still cast. I did some of it (to get key) and I don't want to go back.

So melee isn't bad. Moving melee is really bad. Just do what you like, you will have to put up with them for lots of levels, so do something you like. I can't wait for 5 DKs.