No haven't seen one of those , but have one of these on my scope.
http://www.kineoptics.com/HC-2.html
This was given to me for free by an American astronomer when I built my Newt and have never got around to replacing it.
I find it a great focuser and was able to maximise my FIF when designing the scope due to the low profile.
It does how ever rotate the eyepiece when used.
That is not normally a problem except that i am getting a TV Dioptrix and won't be able to use this focuser any more due to the rotation and am in the market for a replacement.
Getting one of these , again due to the ultra low profile and long focal travel , and no penatration, but the $$$$$$$??????
Although it's only a little more than a Feather Touch
http://www.clementfocuser.com/pages/2/index.htm
need deeper pockets
Mark
p.s. if you have a Dob don't think about the clement unless you have a car jack under the tube to keep it up.