I would be skeptical of the survivability at this stage in arena. One thing you do have going for you is lack of facing issues for your core spells.

When I did this it was great in large battlegrounds, mostly because I can get the jump on people, my location is unknown, and there are other damage factors occurring that lend themselves to helping out (your worried about the rogue or warrior beating on you versus the 15 debuffs you just got).

That was also when drainlife was aided by 'affliction effects' versus 'your affliction effects', a fully doted anything short of a boss was over kill once drain life starting occurring. Their health looked EXACTLY like your casting bar but in reverse.

Incidentally I didn't get much in the way of killing blows, as burst damage people are pretty sly about executing your mobs once they see you doing that (kill shot, execute, etc)