I ran WSG a couple times with my twin shamen in the same bracket; did surprisingly well, people ALWAYS focused on my leader, I'm sure expecting me to be crippled once killed(till I alt-tabbed to the 2nd and it's skill suddenly skyrocketed past "/ASSIST LIGHTNING BOLT LOL" to "EAT EARTHSHOCK AND FROSTBAND YOU SON OF A BITCH RAWR QUIT RUNNING PANSY YEAH IM NOT A HELPLESS BOT NOW AM I" =x)

Having the extra and focused "Oomph" is nice when your allies distract the enemy long enough to fire off a shot or three, I took down quite a few despite being below the bracket's lvl cap by a lvl or two; the main issue you will have is delaying respawns. Unless all chars die at once you're gonna be useless on one or more chars till they're regrouped; Typically, I left my extra shaman lying dead till the 2nd died(which could be 1-2 respawn waves later) then released both at once; if you release the dead while the others're still alive and away from spawn, you'll be vulnerable/useless on the main till you get the alts caught back up.

Keep that in mind, people may blame you as well for taking those extra slots, the only BG we're "welcome" in is AV where the numbers aren't so limited lol(Depending on your setup; 2boxing would be fine in any really, but 5 is a huge pain even in AB where you only need 2-3 defending at most, unless you can convince the others to defend, which isn't gonna happen if you're alliance)