Yes, let's all over-react to this.
I play both a commando and merc with full heal specs. I will absolutely die in 1v1 every time especially if I'm spam healing myself. (My mother told me I'd go blind that way...).
If my shield is up, and my stim is up, I may last a little longer, but eventually you'll dps me down. Particularly if you interrupt me a couple of times. A good teammate will see the healer getting wailed on and come to my aid, but those players are surprisingly few and far between.
There is no way heals are overpowered. Cast times are ridiculous, even with a (in retropsect, pretty useless) alacrity build. I lead the world in healing the recently deceased, and again, I'm an easy 1 v 1 mark. Interrupt me. Be patient. You'll get the kill.
(I should note, also, that I'm usually not concerned about myself. I'm usually healing my teammates and would rather take the death and get the last heal off on them if possible. So I only "turtle" if I'm alone, like, guarding a turret or door...). So again, easy kill!