The primer works fine, use it all the time. It will build up on the end of the needle from time to time, but so will most paints. Have never had to break down the airbrush while using Vallejo Primer to clean it, unless it wasn't cleaned well when I put it away last. I put it through a H&S Evolution, with a .2mm needle/nozzle, at about 20psi, works a dream.
Would never know the snap tite Revell Tie Fighter I am working on was a snaptite with the primer on it!