I'll be curious to hear as well. I will be shooting the Big Game left bevel heads this fall. There is enough endorsement on Jim's site but always fun to hear more.
I have developed some creative ways to sharpen the BG heads and have them shaving sharp. I hone the inside radius of the BH on a 6" PVC pipe cut in half with 400 wet/dry sandpaper wrapped over that outside radius of the pipe. I finish honing on paper grinder wheel.
You can change the tip configuration on the B-Ax & B-Game heads to that of an Ashby tip. Bevel on opposite side of tip from the main bevel. The top BG head has an "Ashby tanto" the bottom is stock from Centaur.
Kris