Like others, I use the bolt stop on my MKIII's to release the bolt. I use the slide stop as a release on all my semi-autos with the exception of two S&W Shields as they are almost impossible to use as a slide release.
Reading through this string reminded me that the owner's manual for my Coonan 357 calls it a both a Slide Release and Slide Catch. The operational portion specifically states to release the slide using the Slide Catch.
Manual for the Colt says to grip the slide and pull rearward. Don't think I ever read that manual before. In the Navy they always trained us to use the slide stop, so that's what I've always done.