I think there are a lot of viable arena teams out there for multiboxers. The popularity of shamans is probably due to the fact that people know it's possible so they don't give up as quickly. Likewise, the nonboxing herd doesn't stray far from the FOTM groups popularized by other people who have proven their effectiveness. Any melee group with 1 or more DK's and a healer, any casting group with enough burst to kill in the span of a GCD and a healer is going to be viable. I just stomped a 2200+ team 3 times in a row with a 0 healer team. Just wait until I finish engineering =)