Hi Mike,
Cabelas has a Creek Company Round Boat Float Tube for $59.99. About $68.74 with shipping included. If I were to ever get one, I think I would get this one (it's valves also match with my ODC hand pump). It seems to me like the U tubes would let water from wakes rush in the front when the donut tubes wouldn't. I know the U tubes provide for easier tube entry rather than step-in donut tubes. I don't know since I've never had one, but since you seem to be familiar with them, maybe you can give me an idea of some of the advantages and disadvantages between the tube types. Thanks.