I've been offered a surface grinder

[PixMan]

I would only use those holes for lifting. Putting a stop at the end like that could stop a part you're grinding from ejecting out the end in the event of a tragic mistake, jamming work between the stop and the wheel. The result could be a blown up wheel and chunks of aluminum oxide hurtling at high speed in myriad directions. Better to let the slipped work just sail off the end of the chuck and fall harmlessly off the end.

I still maintain that I've never seen an end rail used. Here anyway. Perhaps it's just a local thing, but having worked at the biggest maker of grinding wheels in the world, I know they never used end rails either.