For spi epoxy I recently use my titan 6 stage sprayer at work, which I didn't buy for automotive paint. Other than overly tired user error & possibly the 3 year old epoxy is a little less than perfect, it sprays pretty good with it's pressure assisted gravity feed gun. Definitely less fog than the 1.8 vapar gun. I can see where even a low production shop would be better off with not having a cheap gun for epoxy, especially for sealer coats.
Now for the poly primers you really do have to sand a lot anyways & really have to be careful not to have mixture drying in gun, so even for a production shop an expensive gun would be less important for it. Last week I mistakenly grabbed a 1.8 vapar thinking it was a 2.3. took forever to spray what I mixed & last part started drying in gun. I then remembered I had last used an old canister gun I enlarged spray tip on for evercoat poly. Had a 10 pack of canister bags to not have to clean out canister. May try a larger tip set in the titan turbine sprayer. The pressure assist , which the accuspray guns also have, really helps push thicker stuff & not fog the air as much.