not sure about the question, anyway
I'm since the MOS-PuP release in an enviroment, where AmigaOS has the higher pri. (4)
Few days ago, i've tryed to set MOS as higher priority (testing) but i've noticed that if i wish to boot in AmigaOS3.9BB2 (using the Boot Menu) i'll achieve always MOS instead.
I thought thats quite normal, due the dual AOS3.9 SetPatch dual reboot.
To be honest, i haven't tweeked so much to fix the problem :-)
PS- probably i should enter in the Early Boot Menu twice but . . . its already OK for me.
EDIT- ah, forgot to mention that i have IDEFix installed on AmigaOS (LoadIDE)