just started 2-boxing last weekend with my hunter and shammy who were leveled separately to 70. haven't tried arenas yet, but am actually doing really well in bgs. pretty stoked about it since i really expected to get my double-ass handed to me in there for a while. the trick is, my shammy is resto(18/0/43) so i'm doing separate roles with each.

my hunter (0/43/18) is my main since she needs to do a lot of dancing and jump spin shots and such to kite. she still does good damage since her controls aren't that different than when single boxing. but my shammy slave was the big surprise...he's getting top heals in the majority of maps (even when i'm running with other single boxing healer friends-- to their mild dismay). part of this it due to how OP chain heal is in bgs (bigger the crowd, the better it is), but some of it is due to my set-up, as well as the fact that i'm a healer with a full-time body guard (and a sniper with a full time healer).

i basically just treat my shammy as a meta totem. lead him into each combat and try to park him slightly back and as hidden as is convenient (often not so much, but what-ev he can take a punch). he drops his totems while i send in my boar and start bouncing around shooting faces and generally making a terrible nuisance of my belfy self. i have hotkey'd heals for directly targeting my hunter, her pet (this one is 'co-keyed' with mend pet), and my shammy himself. then my generic heal keys (q,e,r) are set to heal my mouseover, or my hunter's target's target(the right toon to heal in 85% of cases), or my shammies target lacking those. on top of all that, i use clique on my shammies raid frame to do heals as well. the redundancy may sound like overkill, but it allows me a lot of flexibility as i can pull off heals regardless of what the hunter is doing in terms of mouse or keys. whenever heals aren't needed, i just hold shift to add my shammy's spells to my hunters attacks to get that often decisive extra chunk of damage down.

i'm levelling up a warrior with a warlock slave and plan to up to 3 or 4 accts once i get them to 70. if i just go three, i'll be running the same combo as you. though i'll prolly keep my hunter as main, since i actually feel that with her range requirements that she needs to move even more than the lock. i'll prob do a mixutre of dropping the lock off with the shammy and occasionally just having her follow and pop off her instant dots so i can keep on the move.

i plan on trying out arenas soon, but know for certain that they will not be forgiving of my decreased mobility when 2-boxing. i mean, arenas are hard enough when single boxing. anyhow, there is no question that 2-boxing is making me a better player. when i switch back to run arenas single box, it feels like easy mode.