Some simple advice.
Buy 3 gun's. 2 at least.
Primer,Paint,Clear or Primer,base/clear and you'll never have a problem with cross contamination.
Especally primer as it's 3 times as hard to clean out than base or clear.
You can spray primer with a 1.3 IF you want but you don't get the build like with a 1.7-2.0.
Besides, After doing some paint work you'll be addicted like the rest of us and it won't go away.
You'll be painting everything in site once you get into it.
jc, Could you elaborate on what/where on the "universial" bag set-up?
I have it on my 'D and love it but haven't been able to find anything that fit's other gun's.
DON'T use the Hefty type "slide lock" bag. They pop open from the pressure (?) when you shake it up. Defeat's the whole concept.