I tend to stay with what works well for me. I use the Spray-it gun when I need to use a portable compressor as it does not consume that much air. When at home I use my Devilbus Finishline with my big Quincy compressor.
As for product, I have shot waterborne finishes from Target, but 99% of the time I shoot pre-cat lacquer or a conversion varnish - I use a 1.3 tip and 23psi at the gun for both. If I must shot color, I use a colored lacquer with the same setup. Hope this helps