I use the gray pads to finish off with. I get it right with the guide coat and check it with grease & wax remover to SEE if I've got anything way out that needs more work with paper and then I use the pad with the Ivory liquid soap or as Milo likes Ajax and "finish" the whole project.
Custom paint is just,another stage in the finish phase. We have to take it to the next level cause it's really put thru the N'th degree and scratchs are not well recieved.
It's overkill on repair work and I'm NOT saying collision work is sloppy but it's just that you don't have the time,or money for that fact,to dick around making it perfect. Repair work is an art to itself just like custom is and I would probbly suck at a repair shop cause I'd be spending way too much time on a job.
I had been using the scotch pads for scuffing but Bob turned me on to using them for finish sanding after a scratch issue I had and I just took it another step using them wet kinda by accident as I was using a red one to clean a panel after some blocking and was surprised at the finish left.
I still use Nason solid base but if it's a metallic or a special color,Chromabase is the choice. One thing with Chroma though,it is a different base and IF your sanding is not up to par,it will haunt you. Nason actually fills better,maybe cause of more coats,but I believe it's the enamel it's based on which does a better job of filling than Chromabase. I've learned to use Nason's reducers to MY advantage and I actually will use Basemaker instead for reducer if it's in the price range of the job.