I think I agree with bugbyte on this because I think the simpler the better. I dont want to have to look down to figure out what I want to do with a nav knob. The Powermate is also more like what you would find in a regular car head-unit, you push for play/pause, rotate for volume, push-rotate for next song etc. If you want to do more just install some more buttons that are separate. Thats what I plan on doing.