I really admire the glasslike clarity you can get with lacquer, but poly is what I use for its durability. The nitrocellulose that difalkner uses is made to be sprayed and has to be modified to be brushed due to the extreme volatility of the thinner which is also a concern for its toxicity. Poly is formulated to be brushed and needs to be thinned to atomize well. As it is thicker, I find it works better in a pressure pot. Poly has adhesion problems over some finishes and cure issues on some tropical woods. Lacquer is delicate, and poly is tough. Lacquer cures fast, and poly cures slow. If you are going to build a finish with several coats of poly, you will need to sand between coats for best results. Not sure how that works with lacquer. There's a narrow range where a wet coat of thinned poly will hang on a vertical surface without sagging.
Couldn't agree more, John. I like the delicateness of lacquer and how it bonds to each previous coat. I can spray it thin, thick, with slight orange peel (on purpose), so that it flows wet and smooth, etc. just by changing a few settings or viscosity of the mix. Poly looks like plastic coating to me and I have never taken to that look. That doesn't mean it's a bad finish, it just doesn't appeal to me.
And curing fast is important for me - less opportunity for dust to attack your finish, quicker to get jobs out the door, probably more reasons but those two come to mind first. I can spray sanding sealer, wait 10 minutes, and begin sanding for the next coat of sealer or the first coat of gloss lacquer. I don't think you can do that with poly.
All of these reasons are why I also like a French polish finish with Shellac - thin, delicate, each coating bonds and melts into the previous coats, quick drying, easy to repair, etc.