Do you have a hopper extention for the combine? That is a great productivity enhancer IMO. Reduces unload frequency.
I have not tryed the Bison rotor, but the gleaner guys sure seem to like'm. If I could get one to try, I'd take the time to swap it out and give the dealer the time they want to research its performance in my area and crops.......? It looks like a great, versitile rotor.
I know you have the afx, but give Ron Kile a call. http://www.kilemfg.com/
He now has a kit for the afx that is supposed to increase the throughput and reduce the stalling at the concave transition. See if he can provide you with more info on it and maybe it will be of interest to you.
Soon Ron will be working on a rotor vane setup for the afx. He is combining wheat right now, so you may get his wife or shop guys, but he will return calls as soon as possible. Dont know if these are of interest to you, but they sure worked well for me this year in my crops and climate. I ran crimson clover, tall fescue and winter wheat with them so far. I also now have a short set of forward rasp bars that are the same size and style as the reverse rasps. I hope to run a few acres of soybeans I have and some corn this fall. Next year I will remove my gorden bars and run all Kile bars. 12 reverse and the rest forwards.
EDIT: I run the specialty rotor, but the new bars will fit the afx and have the afx ramp angle.