Ed, I've been around 3 different brands. My neighbor used the Quickcrete epoxy floor kit about 10 yrs ago. It still looks decent with a bit of lifting where the tires run/sit. Now it was on old concrete and I don't think he did enough prep.
I we did my buddies new parts store floor with Sherman Williams (rather expensive too) on new concrete. Proper prep, with in 2 years it was flaking off where my soft wheel roller chair was behind counter and out front where the bar stools sat.
My buddy Tom did the new office down at the shop 4+ years ago with Rustoleum garage grade kit w/ optional clear coat for drability. Old concrete on the old mechanics side so it needed extra prep to get the oil etc off. Probably prepped better than most people would do. So far no chipping or flaking at all. It gets pretty heavy traffic w/roller chairs and 2 bar stools. I spilled my ice tea while getting a refill, floor wasn't slick to walk on. I mopped it, never noticed and slippery. But i guess any floor coating my be slick with oil or water under the right circumstances?
I see Rustoleum now has a "proffesional" version now that wasn't available or at least didn't know when Tom did our office.
I'm sure there are many epoxy brands out there, this is just what i've tried.
Hair line cracks should be fine. Tom started with a light coat in the hairline crack first, let dry then did floor as per instructions. Rustoleum does sell a crack fill product for larger thin cracks.
First pic is shop office now, the close up of the just a smidge bigger than hair line crack under.(no filler)