Hi, Simon
I am facing the same problem, with the announcement about Testors cancelling their Model Master enamels line. I am long time user of Testors paints (from my balsa flying model days, even before there were plastic models), using first Pactra enamels, but then soon moving to the Testors ones.
I have two objections to acrylics. First, they occasionally dry in my airbrush if I am not super-diligent about cleaning it as soon as I am done spraying (even a distraction like a phone call has led to clogging. Secondly, I often model airliners, and autos, which call for glossy finish. I cannot get as glossy a finish with acrylics as I can with enamels.
My friends who are more experienced with acrylics say the addition of retarder to the acrylic paint will solve both of my problems. They say they have no clogging problem, and get a glossier finish. Sounds like it will make life easier as far as airbrush clogging). I am still not sure their gloss acrylics are as glossy as my enamel finishes, though. I may have to resort to clear coats, though it is so easy to overdo those.
I have not tried the retarded acrylics yet, but I'll post with my impressions when I do.