Yeah, if a max level forcefield could not withstand the hits, I have no clue how the other squishy classes could survive at all.
That is the only way to use it
I run in and build charge and pop it once my health gets really low. The healbot will top me off and I can get back to 5 charge before it goes down.
I usually spam my attack flame thing, which always resets the charge counter. Works fine for most enemy groups on veteran (NG+ now) though. Only got issues with boss encounters, where your tactic might work better. Whats your main means of attack?