I've had a couple. PK healers, and Support Healers which the build is "built for".

Going human for the PK range is going to help, progged weapons/armor and you
can actually be a real force if you have some basic chasing skills. Gate can be
overpowered on an aggressive healer.

At hero? Probably elf in my opinion. I had a wood-elf healer to hero... wigglebottom?
He did alright. Plenty of pk's with sanctuary beastcall and chasing people down with
exotics.

If you want to go support, but be great at at, I would go gnome just for the mana.

And sneak is useless on a healer. In my opinion sneak is for utility/offense, or fleeing.