The RH96 works does everyhthing it can for the 15,996, 330, and 396. You loose out on some of the XT's functions since the screen will not do the color change. I would guess that maybe a RH96XT is in the future?
Come to think of it, the RH96 has an extra serial port that is only used for upgrades. With a little code change, this could be used as a GPS port and the RH96 could do this 'multiplexing' as well. Upman, are you listening?
This would be GREAT!! - but the 396XT would need to be able to read the incoming data as GPS and send OUT RH96 control data simultaneously... WOW - I bet you could sell quite a few more RH96 heads with this capability!!