Most means more than 50%. I know of one, and I'm sure there are a few others, but it's still nowhere close to "most."
if you are going to a pro shop, as in "professional," and they have a Sparx, as in "reasonably priced convenient home machine," you should find a new place. Sparx takes more metal off, and it also doesn't go as high up on the heel and toe of the blade as a professional sharpener should.
The only way I would be happy to see a Sparx in a pro shop is because I don't trust most places to do a consistently good job. Sparx is consistent. It isn't "professional" level.