I have used lacquer primer for years, as I have 2K primers.
If applied properly and sanded well, lacquer works fine. Or, it does for me. I use black lacquer primer for a guide coat as well. It dries very fast, sands easily and is cheap. About $40 a gallon. I haven't found any 2k that cheap.
Another thing, it does not set up in the cup. That's why I keep some in my syphon cup. It's easy to just grab the spray gun and apply a little primer.
With 2K, you have to use it all or waste it. It will set up in the cup. I just can't see pouring out good money because I mixed up a little to much 2K.
Shrinkage: If you lay the lacquer primer on really thick, you will get shrinkage. I usually spray on light coats, and sand in a few minutes. It fills small imperfections and blends the edges of plastic filler very well.
2k will shrink, it too has solvents in it. Down side, you have to wait several hours to sand 2k.
If any one can tell me where I can get 2k primer with it's activator and reducer with shipping and handling for less than $48.00 a gallon, I will surely be getting some.