I've tried taking my kickboat out in the ocean several times, in waves up to 4 feet. It's very stable, very safe, and very comfortable. It seemed easier to launch, was faster, and held more gear than a float tube. The only bad part is it's very difficult to clean all the saltwater off of it completely, and any steel part is going to rust very quickly. Luckily the frame on mine is aluminum, but the oarlocks are steel and got crusted with rust after only a few trips. Overall a float tube might be better for the convenience.

Nico