Glasurit has a GREAT reputation and I know nothing to contradict that. That said, as was suggested, let the shop use what they use. They'll have the compatible reducers, accelerators, etc., etc. and will know how it should look, feel, spray, etc. And, as mentioned, they will mix or buy it cheaper. If you are concerned about color match, have them do a spray out on a small card before they paint the whole thing. They shouldn't mind if you are willing to show up when they are ready.
I have a preference for base coat/clear coat, and imagine most shops will. That said, it you don't want that, it is your money, and they will be happy to oblige.