Wait, they stripped the bolts and still charged you the full $400? That's wild, because a threshold ramp is one of the simplest installs out there, and if the thing tilts under a chair that's a safety issue, not just sloppy work. Sounds like that company saw "accessibility" and figured they could charge a premium without knowing the basics.

Cheap stuff works when nobody's watching, same as everything.

That bit about the slow cure cutting down surface dust is the part people sleep on. I did a 10x12 pad last fall and kept it wet for 6 days instead of my usual 2 or 3, and the difference in the finish was crazy. No chalky dust on your hands when you rub it, and the edges didn't chip when I dragged a wheelbarrow across them. Bob's slab by Riverside Park probably sat wet even longer with that Spokane shade, which would explain why it felt so hard. Water is free, so why rush a pour and fight dust for years?