Hi Boylston
well, i think that, when running a 3dps 2 healers, u somehow gotta have some heal reduction effects...a warrior, hunter or rogue can do it. If u dont have i really dunno how much u can nuke, and if it will be enough to put one guy down.
running 3 shaman, 1 druid boomkin and 1 resto...well, imo the druid is a top class in arenas when u play it solo. u gotta shapeshift, run around, make charges, cyclone, apply hots, apply dots..what im trying to say is: will u be able to control ur shamans along with a druid, making quick casts and reacting to the opponent as well as if u were playing the druid alone ? I really dont know how effective it could get, need to be able to nuke and cc all at the same time, the same person...

A boomkin can be a great addition to ur team, running 3shaman+1boomkin boxed, but, is it worth it? +5%crit...and a bunch of tools that i dont know how good a guy can use them in arena while boxing... i guess its up to u to make some tests.

I can only say that, 3 shamans and 2 resto can cause arenas to last forever :P