Yeah, it's probably under stacks of stuff, like "Modern Bureaucrat" magazines, and had coffee spilled on it...
I'm sorry, I shouldn't think like that.
My shop floor ranges between 5" and a little over 6", of, I think, 6000 psi concrete with "elephant hair" fiber mixed in. The plan was 5", but, the amish boy on my tractor got carried away dragging the fill out in the back corners.
I have never "finished" my floor with anything but concrete sealer, for the same reasons you stated. The gloss white epoxy I've been around and worked on is at the local airport. It has worked real well, there, with moderately heavy jets on it. No blue-tip work at the airport, though.
I finished the floor on my attached garage with simple rustoleum floor paint for garages purchased at Lowes. It also has worked well, no signs of wear after three years. If it does start to look bad, I would probably use Racedeck over it.
When I do any heavy duty torch cutting or grinding inside, I slide a heavy sheet of steel under the work, so as to protect the floor. I do have a couple of scars, were heavy parts, like rear ends out of big trucks hit the floor a little too hard. I've found that small chips and scars can be repaired permanently with JB weld. Just use it like body filler, then sand it smooth.
Here's some pics. of the home for the gen 1 Camaro's. Same size as your plans, I believe, but, I think 10 foot walls.
Nice details, full slab out front. I like the colors he picked. Small AC cools the whole shop.
Steve.