I won't. Because I already am.
And to answer the OP, I have been playing both factions for years already. My horde toons are currently on the bench though. I'm not waiting 15+ min to play a BG. Pretty much strictly alliance lately.
Racials will make the difference for the min/maxers that play at Glad & higher, despite what people think. It won't matter much for the rest of us, however, these players are the ones that 'set the trend' if you will. If they switch sides you can bet scores of people will follow (it's already happened back and forth).
i used to be alliance, and here are the reasons i will never be alliance ever again.
humans - they think they run the show (they dont)
dwarfs - too busy yelling at each other and trying to one up the other clan to care about others
night elfs - pretentious douche bags
gnomes - you feel bad for them but they dont take any action for anything, whimps
draenie - space goats who couldnt handle their own problems, so they brought them to azeroth. push overs.
worgens - hermits who shacked up behind a giant ass wall until a giant dragon put a crack in it.
You can tune a piano, but you can't tuna fish.
I'm curious if the Shadowmeld + Camouflage combo will be popular in WoD? With Camo healing 5% HP per second in WoD, it seems to be a very good BG strat, perhaps less so in Arena. I know you can pop Camo in combat now, but having the ability to "vanish" and get out of combat and heal back to full is pretty huge for BGs.
Its certaintly a boost to survivability for hunters, but any damage (dots/bleeds/melee attacks) and you will lose camo instantly.
As this is the case a dwarf hunter with stoneform will be much better at it.
-> fegin -> remove all dots and camo 18-20 sec later and your at full hp
In BGs, a hunter leaving combat to stand in the corner for 20 seconds to regen to full is less of an issue - so it might apply there.
Re: Shadowmeld, I can tell you now that Shadowmeld + Flight Form is one of the most annoying things in what little World PvP that remains in MoP. Get jumped by a Feral, start killing the feral, SM + FF macro comes out and he they fly away...repeat about 2 minutes later...repeat...repeat.
But as was mentioned above, stoneform + FD + camo (with glyph to move) is pretty good (in theory) even if it's only 10 seconds. That would give someone 50% of their health back, and if they're running Spirit Bond it'd be 65%. That's pretty nutty, completely theoretically, but still nutty.