Full ranged is easier to multibox. Full melee is a challenge to multibox in any game. You can do it, but it's more difficult due to AOEs. It's also nicer to have a mixed group so you get the most use of the gear that drops.

I don't use mercs, but I like have two healers in my group. The healers in EQ2 do reasonable damage, so it's not detrimental.

My current group is SK, Troub, Wiz, Illy and Warden. A friend plays an Inq with me. We are now just starting Luclin and are L90. Luclin has been the most challenging so far. They really upped the difficulty and "gimicks" with bosses. I think a DPS boost will help though as my gear is pretty bad, and the Luclin gear is a huge jump. I think you can get pretty far with 3 mercs, probably even moreso than six boxing.

If you want parses check EQFLAMES.