I have a box of Avalon King coating sitting in my garage, but I have been terrified to put it on until I get the base paint "just right"... so I haven't had the time to work on it... but I guess your comment makes me think I'm doing the right thing to wait until I have time to do it right.
I have not used ceramic coating on my XLR because it's paint is older and the color is black with a lot of minor age imperfections and touchups that I can hid pretty well with waxes. This is my opinion only, but I would sand and respray the XLR before ceramic coating. Lighter colors on XLRs wear better but these cars are getting older. Ceramic coating is wonderful for newer cars, but it really highlights the paint quality.