One thing to keep in mind is a 8680 is a gleaner designed combine. i dont wanna start any fights but if some of the things that are giving you trouble on the 8680 are on the r72 chances are you could end up with some of the same problems. Just one way to look at it.
R72 is a rotary and much simpler than the conventional C62_MF 8680. I don't know what crops you run but in straight cutting wheat, the R72 will far outdo a C62. Ed in Montana