I have an Earlex 7000 (three stage).
I have put only a few materials through it before shelving and going back to my arsenal of air guns I used during my car painting days.
I will give it another go eventually as I know I never got it anywhere near dialed in.
I do (now) have a full set of needles which I need to try out.
I think my first, and biggest issue is getting used to the heat in the air. Really messes with my reducing that I'm use to.
The big thing that attracts me to the pressure pot (aside from the ergonomic advantages mentioned by Kelly) is to solve a problem I had early on with the spray gun. I found that there is a bypass check valve that connects the incoming air into the cup, I'm assuming it is to help with feed versus being pure siphon.
Anyway, I had poor feed, etc. so I pulled out the spring and check ball to get more pressure in the cup and that fixed the issue.
Again, a list of things I need to spend some quality time and try to properly address one at a time, I'm sure the outfit is very capable, I've just never given it a chance yet.