The lack of lower speeds would bother me, even if there were no other
negatives. And since the motor(s) seem to be built in, that would be
hard to change.


They are not built in. A single motor is on the back side with a step pulley
belt drive system. A push-pull spline clutch selects the lathe or mill. Like
you pointed out, the speed selection is rather limited. But since this version
does not do threading, not that much of a limit. You really shouldn't be
turning any large diameter items on it, so a slow speed of 500 rpm seems OK.

The drive system of the Grizzly has more speeds and a much wider range.

--
Dennis