Interesting...this depends on the money you have to spend,and the effect you want..Back in the bad old days of acrylic laquer,we always treated a black paint job with respect,,they always needed a wee bit more prep,and yes,,the grit of the final rub is always important..I always used 320 dry on the final primer coat,hit it with three or four coats of color,then the next day,knock the top off it with 800 wet,then give it a few more coats with 50/50 color and a good quality clear,then a couple of days later,1200 wet and machine polish,,Always had a bit of depth to it..If I wanted to do a black repaint with todays materials,I would go base coat/clear coat,for the same reason...the depth of the finish,which I personally think is a whole lot nicer than a solid color with out clear..Just buy GOOD quality materials,if you have Spies Hecker/Standox,or DuPont,any of the big brands,including the two pack clear..No one ever regrets buying quality.I have used DuPont Nason,and found it to be a real nice clear to polish up..