I don't use a healer anymore.
I don't even have any healers at a usable level on my alternate account. I almost always finish GW.
Every once in a while I will throw in Old Daka but even at G10 she gets targeted and taken out too quickly for my liking.
It's easier to dominate turn meter (and a lot of fun to crush your opponents).
Leads I like to use for GW:
Sidious
Wedge
Phasma
Teebo (if going against 5's, Dooku, etc.)
EP (hard to come by I know)
Top DPS I like to use:
88
86
GS
Lando
Biggs/Wedge combo
I like to use IG-88 with Old Ben. He hits like a truck once OB throws his Mind Tricks down.
You CAN use healers but when you get to top tier teams, healers can't save you. Wiggs one shots, Lando crit AOE 20k plus damage. There are no healers for that and that IS what you will eventually end up with in GW.