bej,
We got the 2670 GB rigged with engines but never got to launch it because of the early ice situation by us this year.
My test will have to wait until April or sooner if I sell it in a warmer climate.
There were a couple of posts from another GB owner that swears by them. They are a much better looking and better built piece then the Doel Fins are. A have a customer in New York with a 2670 Gb that also swears by them. I have been told by him that they offer a higher and more fuel efficent cruise speed and a 2 mph increase in top speed.
Andy