I had the 300r and it is a fantastic bit of kit, unfortunatly never got around to getting the dvd add on as couldn't really justify it as dont go on long trips very oftern.
I did however get a rather lengthy demo from one of the guys I know well at my local car stereo place and had a bit of a fiddle with it myself.
You wont be disapointed but I do think the touchscreen unit and dvd is a bit steap at the RRPs