"Mike Maxwell" wrote
...

BTW, while the original was a Cass, I don't suppose there's any problem in
principle with using a composite mirror in a Newtonian, in which case a
Dob mount should be feasible.......

Mike,

A few years ago I saw a guy at Stellafane with a home-made (mirrors and
all) 16-inch F/8 RC Cass that was on a Dob style mount. It had a third flat
mirror that sent the light out through the center of the altitude bearing
where the focuser was mounted. The observer sat in a chair to use it and of
course the eyepiece never changed height off the ground. I suppose that if
it had a 'GoTo' drive the observer could sit on the mount and go along for
the ride!

George Normandin