Tried them out yesterday on our 17" Penobscot, as an added safety measure for a canoe/camping adventure with a disabled friend of my sons. They were superb! Canoe was as stable as could be.
They added some drag paddling, but never were in they way of paddling. Would have given a 10, but felt the price was a little high at $100.00, and the installation instructions were a little on the vague side. Called their customer serivice #, the rep had never even heard of the product. Oh well, they work darn good, easy to clip on after the initial setup, and add a huge saftey margin for the disabled on board.