There are a few different powders. You can get a commercial powder that is made for high impact resistance and you'd be close to 100% okay. I'll be honest that nothing is like that ceramic coating that comes on appliances, sinks, etc.
IF it is cured correctly and IF the correct powder is used I'd feel confident in it. We did mostly custom car parts with all sorts of ridiculous colors so wear, impact resistance, and UV resistance was never an issue if the color was right. Because of that we never got into all the specifics with the commercial quality stuff but I know it's out there. Condos and apartments use it on their railings for example, but that's a UV resistant application that you don't need for a sink.
You can have them put a coat or two of clear powder on there also that would help. Car guys are a lot more anal about scratches but you can wet sand and buff that stuff out.
Go to someone that has a clue what's going on. There are a couple powder forums (ColumbiaCoatings has a good one) and you can find someone local that isn't just going to throw it in with another batch and guess that it is GTG. Plus you probably won't get charged and arm and a leg as the big commercial guys HATE cleaning their guns out to switch colors/powder for your one application.
I'm guessing you'd want it white. Cleaning the guns becomes 10x an issue because EVERYTHING shows up in white, so if you shot a darker color (pretty much any) you may or may not see it. We'd get guys that were holding parts in their hands and go "Oh man, what is that?" Put it 3 feet away under your hood and it's fine. Stuff they'd NEVER see if they weren't inspecting it before they installed it.
Hopefully that makes sense, I've had a couple too many beers tonight