If you're using AA for EFFICIENCY, you will need a lot of haste, and you'll still be able to trim waaaaay back on spirit. What I mean is this: I build stacks and pop AA as often as I possibly can without wasting it. Archangel often beats shadowfiend on my manareturn. However, time spent building AA stacks is extremely slow for mana consumption. Basically, if you do this you get more mana back + spend less mana. I stack haste and mastery pretty evenly and carry around 2200 spirit. Yes, mastery has almost no impact on Atonement. No, Aegis is still usually my top heal.
If you're saving your archangels, which seems to be the typical use (but to me this only makes sense sometimes), you won't be in as much of a push to build stacks often. I think it'd change the stat priority quite a lot, so someone else will have to comment on that playstyle.
Again, with disc, it's all about your healing breakdown and what you spend time casting. Remember too that AA spec is hard to get good rapture timings with. Especially if there's another disc in your group.