I have both a Rolair JC-10 and CAT 4620A. The CAT I was very hesitant about getting due to quality control issues. However, it was the only "quiet" model in the price range that was still portable and able to put out over 5 CFM @ 90. I got lucky I suppose - no problems and has been working great.
On the flip side, I have been having an intermittent issue recently with my Rolair - it often fails to recharge automatically unless the switch is flipped...need to troubleshoot that at some point.