I have put one on the VS. You can see it here: http://gikonemp.blogspot.com/2008/01...ted.html#links
I doubt it is as bright as the Whelan because the current draw is less, but it appears only a little less. It is not as robust but more than adequate to my mind. A lot lighter and cheaper.
The Kuntzleman fitting is more appropriate to mountiong on the fin.
PS If you click the pictures you will get a better view.