Quite some post you got there...
I have the same things to struggle with. I have never ever even come close to the healing output of a RP (or WP for that matter). I am not totally specced for healing, but still, I doubt I will get close if I would. Highest healing I pumped out in a scenario is around 40k. RP's can get 100k with 'ease'. It may also be playing style, I dont know.
I also have a tough choice between Vaul and Asuryan. But also noticed [spell]Cleansing Flare[/spell] and playing a lot of TA now, I definately want that! Don't know how useful it will be once I cant play TA anymore though. But heck, I'll respec if it turns out less usefull after that. Got enough gold to burn anyway.
What it comes down to IMO is: do you want a fun char to play or do you want to max out your char for healbot (less fun in my perspective). If you want to have fun: offensive specced AM can do that for me. I had games where I put out 20k dam (and 10k healing or some), which was pretty satisfying for me.
One thing I hoped to find in this guild is having fun. Healbotting or else (i.e. nagnagnag, you dont heal enough) isnt much fun for me.
And dont understand me wrong, I try to keep ppl up as much as possible. But sometimes I'm just too busy having fun and casting destro to bits and other ppl die. Just like tanks and DPS are sometimes just too busy smashing skulls in after which they look around just to find some witchelf standing over some very dead healers.