My main concern would be the wheel used. Grinding steel is a sophisticated
art as practiced by most, and an interesting science as practiced by few.
You need to use the correct abrasive, binder, surface speed and maintain
the profile regularly (unless a bonded wheel). Otherwise, you'll at best
have a less-than-ideal edge or in the worst cases either a re-tempered
tooth or abrasive grit embedded in the steel (which which dull your files
more quickly during touch-ups).

I have a Foley Filer which I purchased only for it's cheapness and
proximity (I was already at the estate sale on the last day and the seller
was getting desperate). I can guarantee that I can sharpen, by hand, a well
maintained saw faster than I can set up the Foley to run. My only intended
use for the Foley is re-toothing using a modified holder (in the some-day
project folder). I can't speak to the S&N but I'd assume it will be limited
in usefulness. The Foley won't match the contour of breasted saws but it
will somewhat follow the profile of the rail, if any.

B.J.M.R.