Starting out 6 boxing, especially with melee and ranges, and a bunch of the foibles that go with it, it can be easier to use 6 of the same, or 1 tank and 5 other ranged.

Personally I found, when starting out, that running around with 6 RK's or 6 Minis, stomps over just about anything. In the later area's, where you need a tank, it can be nice to have a Guard or a Capt up front with 5 RK/Minis in behind. The Capt is a little weaker, but the bonus's are pretty decent, and if you can play it right, it works well.

Managing a fully diverse team is harder, because they all have different skills, that have different cycles, and you need different placements, as well as having the setup to change targets for some of the ranged guys but not your tank, which hopefully is keeping a load of agro. Most of this comes down to learning about the capabilities of all your team, as well as how to setup your control of that team effectively, and making sure you are monitoring everything going on, rather than concentrating on your little bit. The play style is a bit like some of those Korean StarCraft competition players..