As stated earlier, you should stack your stats in this order of importance;
Cunning>TechPower>Crit>Surge
if you look for those stats, you should have no probs healing HM.
I am lvl 41 and my cunning is at 750, Tech Power 820, Crit is at 36% (unbuffed), Surge is 70%. Wearing all orange or purple with Purple mods. I out heal lvl 50 troopers, Smugs, and Sages all because they don't know how to stack their stats.
When Buffed and stimmed up, I crit heal every other heal and I never run below 60% energy. It's all about how you manage your heals, IE: dont spam UWM!!!