This is a floor we recently stained. It was a fit out in an existing strip mall for dining area of a rest. Floor was diamond ground, then we used acid etching followed by stain and topped with sealer. Turned out pretty nice. There were a lot of irregularities in the floor to begin with.
I had a sub that did the grinding. They did it the hard way. They had 8" hand held grinders with dust shields hooked up to shop vacs. My back hurt just watching them. I have done other floor jobs guys used stand up grinders as well as shot blasting.