Not being all that familiar with the CAB M, do the cabinet IR and the Power amp modeling have independent engage settings? Nothing wrong with some power amp modeling without cab modeling, if that's possible. In the end, you really should just use your ears and go with what suits you, whatever that may be. My only point being that if you're running a cabinet IR into an otherwise "traditional" bass cabinet, you *MIGHT NOT* like the sound that you hear since the cab IR may be fighting with the EQ characteristics of the bass cabinet/speaker. But if you like what you're hearing, roll with it.