You'll see my team's make-up in my sig.
Previous to multi-boxing the only class I'd played at all was the warlock. I'd never tanked or healed or played any other DPS class.
I'm SO glad I didn't go cookie-cutter with the tank + 4 shaman (or 4 druids, etc.). I wanted to learn more about other classes and wanted the flexibility to play any toon solo. Just last night I subbed in my priest as a healer for a guild run that my mage would normally accompany. It was fun.
The multi-class group does require more research I presume. I spent (spend still) a lot of time determining talent specs, casting rotations, etc. That said, I cleared Gundrak relatively quickly once hitting 80 with my team.
All depends on what you want end game, imho: diversity/drop usage optimization or simplicity/pvp opportunity. (Never mentioned PvP until now, but that I do regret a bit with my multi-class group. Can't imagine trying to PvP with my five man team.)
