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Actually Peter, MANY scope manufacturers are leaving the Crayford behind. Stellarvue is going mostly R&P (now that FT is making them again) and a few others. R&P is the best for imaging because of the weight it can hold without any form of slip, whereas a Crayford takes some efforts to make work really well for imaging - the Moonlite clutch pinion lock (which I have read reports of still slipping with any imaging rig over 3kg) and FT going R&P ans also additional tensioning locks on their Crayfords.
The Crayford design is basically just an R&P with the engagment teeth removed - smooth steel and ball bearings rubbing on (hopefully) flat surfaces to provide the friction required. Smooth, yes, "solid", not always.
I prefer the R&P by far over a Crayford. When you fit the MEF unit to a Tak, the focus precision is as good as a Moonlite, and close to a FT. The Tak standard focuser will hold a 5kg+ imaging load without any slip at all, at zenith angles.
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