Sorry, just spotted this No idea on the difference bud, I was told to use the 200, thats what all the chaps in the US were using. A quick google should give you the differences if you havent already, but I'm sure if the 2 cameras are from the same "family" the 300 will work.
EDIT: 300 is the same camera, but its switchable (on/off), so that you can have a front and rear camera, and a seperate Kenwood control box. If you run the 200 and a 300 you can have the 200 at the rear and 300 at the front and have the 300 switchable.