No, definitely not for Arena (unless you're unusually good, like the guys Aethien linked earlier, which case you can probably get away with a lot). You're certainly giving up quite a bit of survivability. Plus, there's no doubt that nothing can replace Penance as the big heal. But the mobility of this spec is outstanding. Improved Renew, SoL Flash Heals, CoH, Improved Shields, and PoM on the one side, and SoL Smites, SW:D, and dots on the other pretty much guarantee you never have to stand still to cast at a bad time. Combine that with the Body and Soul'd shields and it's like a non-stop dance party.
The mana wasn't too bad, but certainly worse. I can see giving up some healing for better mana if adding crit didn't help, throwing Mental Strength in there, for example, like
this, although giving up the decreased PoM cooldown would hurt.
This is why dual spec was such a good idea. A niche spec like this with such limited use isn't something I'd personally ever bother goofing around with if I had only one spec. But you can learn a lot from these sorts of experiments, for example, that rogues are squishier than they look. DP, Holy Fire, SW:D, instant Smite, awwww sorry, were you killed? By a healer? Who survived your kidney shot? Shame to be you, pal.
Edited, Nov 3rd 2009 5:15pm by teacake