When you say "bonus damage around 670-690" you are talking about the (ranged) bonus damage, not the (tech) bonus damage, right? Because it seems I need to stack a lot more power by sacrificing crit to get to 670~ (ranged) bonus, which means that my crit will drop quite below your optimal range of 38~40. If it's the (tech) bonus you're talking about, well... that changes things.
Ranged bonus needs to be that range. Think that's like 940 tech bonus dmg.
I just observed who scared my melee the most and went off their stats. As for how to play the class, learned that from getting my sentinel and guardians *** beat by Heala million times in a row and then by Celo eventually.