I used the Ranthane...
...yellow epoxy primer, catalyst, and reducer (G2404, G2405, and G2401). I sprayed with the Axis Citation HVLP and gun. All of the internal structure of my -6A got the primer treatment. I found the epoxy primer to be tough and durable...no real issues with the application.
I did find that the contents of the gallon can of the G2404 were a pain to mix to a uniform consistency, as it likes to settle-out over time. Once thoroughly mixed and then the G2405 was added, everything was fine.
I have only primed the internals of the aircraft, no external primer or paint yet. My intent is not to finish color the cockpit interior, but the outside skins will use the same manufacturer (whoever that turns out to be) for primer and finish color.
I presently have 8 hours on the Hobbs, and finish paint will come after Phase I.