Red Stag cow is good meat. Me personally, I would do 100% stag for plain ground meat. Then do 75/25 stag/bacon ends & pieces for bacon burgers.
I don't grind much. Mostly the trimmings. I'll debone everything into roasts and if I run out of trimmings and need some ground I'll grind one of the front leg roasts. When I do grind I typically use pork belly because it I think brisket over powers the venison to much. Mixed as -
Ground for sauces (pasta sauces or chili) - 0%-15% belly added
Ground for burger - 25%-30% belly added
Ground for sausages - 40%-50% belly added