It all depends on your needs. Are your fields relatively flatIJ How big a head do you intend to runIJ Do you ever have muddy conditionsIJ I went from a level land 9500 w_20ft head to a 9610 w_30ft head. I could not have done this in our conditions without the CM option. In our conditions which are hilly (hard on the hydro)and sometimes muddy I wouldn't want a combine with no 4wd. For these reasons I would favor the CM and 4wd options. As a side note, as far as I know, these options are mostly trouble free. I personlly don't know anyone who's had problems out of either unless they were electrical in nature which can happen to anything. My 2c BH