River riding, you DO NOT WANT GPS. You want true over the water speed - which a paddlewheel gives you - not ground speed that GPS will give you. Surfing downstream on a river with 1mph current and GPS will indicate your ground speed (including 1pmh current), so you're actually making the wave of your set speed - (minus) river current and totally screw up your wave.

When you order GPS speed control the paddlewheel is still in the boat, unfortunately the Moomba software doesn't give you access to it. In the Supras it's called "River Mode" - i believe that feature is still there.

The reason that I went with GPS is because paddlewheels need re-calibration sometimes. In my experience, more often when you do a lot of towing - which i do. If you read the manual, you're supposed to put a little cap (included with the manuals and stuff) over the paddlewheel when trailering. GPS is spot on all the time. as long as your water isn't moving. My dealer made the same recommendation though, but i disagree.