Haha. Well, understand I just came out of the 50-59 bracket, and few casters had that many hit points. Assumed, 3k max. That's what our priest has, so I'd figured about that much against an opposing priest.
If I get the first shot off, that's a 2000+ aimed shot crit, otherwise 1000k regularly, immediatly followed by autoshot. If you've played a hunter, you might know that the shot right after aimed shot, for some reason, seems to crit 90% of the time, which is another 500-600 damage. Multishot can then be instantly cast for 400 damage, 800-1000 if crit. That's a very dead priest very quickly, if you ask me. Though, this really only happens if they're caught off guard. That can be pretty difficult to achieve, but it's possible. Though, if they have more hit points, are quick on the fly (aka have a better computer than I do and actually see their health dropping rapidly), they'll bubble. Send in pet, feigndeath+shadowmeld (it can work, sometimes), and then quickly get off another spell once the bubble breaks.
That's completely hypothetical, though. Unfortuately, in a lot of circumstances in PvP, everyone wants the hunter dead. So, I'd never be competing just against that priest, and that priest more than likely wouldn't just be dealing with me.