Mike,
I haven't used the Sherline CNC equipment. But I do have a Sherline lathe I've had for 15+ years. It's a very fine piece of machinery, though quite small. It will handle the type of stuff we do quite readily.
As for quality, the bed is steel with a cast base. The saddle is 6061 aluminum, anodized. The tailstock is also anodized aluminum. Fit and finish is excellent. The motor is PMW variable speed DC with two speed ranges via a drive belt and pulley arrangement, I'm still using the original belt by the way.
I only have the 3-jaw chuck, and I think that is the weak point. Mine is worn out, it will hold small diameter work but will no longer reliably hold anything over 3/4 inch. It will loosen up.
Sherline mills are based on the lathe and there are a lot of common parts between the two. In fact they sell the mill column separately so I could convert my lathe to a mill if I wanted to.
I know this isn't exactly the kind of information you were looking for. But I thought maybe an impression of the quality of the machines might help.
As I state earlier, I think the only drawback to the machines is the small size. That's why I went to the Chinese machines, they simply had much greater capacity. The Sherline quality is definitely top of the line.