If you put the directional pad and transport keys from the mx-500 on the harmony and possibly add additional buttons like menu, thumbs up and thumbs down. I personally think you would have the the perfect remote. I posted something similar on the yahoo harmony forum.... even spent the time to draw a picture (it's also there.) I own both the harmony and the mx-500 (just had to try them both out.) and like them both. I think a mix of the two would solve almost everyone's needs.

-Jason