Hi J_rock
First I must say that I have not had the opportunity to play around with the SG100, so bear that in mind
Your approach of reducing heat input, lowering oxidation seems like the right direction to me. I would continue in this direction, but may be by increasing the primary argon plasma gas flow as well (dependent on whether your nozzle is comfortable with higher argon flow?). Hopefully, this will increase velocity, reducing particle dwell time while maintaining good coating density. A higher powder feed rate may also help.
Let us know how you get on and good luck