lvl 84 toons will always dominate in the 80-84 bracket because there is such a crazy stam boost over this range. I think you will probably get more honor per hour by getting to 85 though and doing randoms so I would probably recommend this.

I have tried both disc and holy for this setup and like holy best. Saying that, I tried disc in 4.0.3 before the shield buffs. Both specs have excellent healing output and variety. If anything I think disc is probably better with the shields from crits and grace. Holy is slightly better for mana regen and chakra is interesting but not really a game breaker.

What makes me love holy are 2 things which really shine in arena but are handy for BGs also. The first is guardian spirit. When teams focus me I will hit this, pop up a renew and all of my instant heals (except desperate prayer) and let the focus me down. Normally I will time this right that at about 6-7 seconds duration, I would normally die but I get the free spirit heal for 50%. At this stage I shield up, sprint off and hit desperate prayer to get back to 100%.

I like this better than penance because some groups will get fooled into thinking I am going to die and switch to a new target and the bonus healing overall just seems a lot greater.

The other great talent is spirit of redemption. In some cases in arena, I will heal more in spirit form than I do alive.

Either way, priest makes a versatile healer and will be successful in either spec. Try both of them out and see what suits your playstyle best.