Aug is less stressfull to play, but you cannot be the only healer due to that aoe mez, instant aoe mez, root... So you may expect not to do much smallman, and wait for a pac healer in any 8-man group.
For variety and utility sake I think tri-spec should be mentioned: 38 Pac 33 Mend 19 Aug
Granted my RvR experience is fairly limited thus far, but I've ALMOST always had a 40+ Mend healer in my group so the 3s cure NS hasn't been as big an issue. Even when I haven't, it isn't always a killer.
With tri-spec you get instant aoe mez and stun, decent healing, plus the first group celerity buff. It's nice for PvE as well since you can do it all - I enjoy my healer in both RvR and PvE and still use him for PvE all the time. At some point if I get bored of using him for PvE then maybe I consider another spec, but right now I'm really enjoying it.
I should also say that I don't consider myself 'elite' - which to me means that I'll run in the group without voice-comms, I don't mind dieing and I'm just here to have fun and play the game how I enjoy it.
Depends on your playstyle. I have a tri spec Healer and feel that it suits me. I don't like popping celerity, but I have the option for green celerity in pve if need be. I would also consider the augH the primary healer of the group (meaning augH primarily focuses on healing/support, especially at the beginning of an engagement, unlike pacH who focuses on CC and interrupt). Both are necessary if you want to be competitive, though pac is more required in a group than Aug.