We’ve used AJ-USA (http://www.ajusa.com/, Mira Mesa at Flanders) twice. Once around 2000 (for my wife’s car before we were married), and once recently.
With regard to the recent work (front bumper and quarter panel and door), I was very happy with their workmanship. Everything looked good as new, color blended properly (I can’t even distinguish the repainted parts from original parts), they provided me a vial of touch up paint for other parts of the car should I need it. They did give me a more expensive quote than Caliber Collision, but I had more confidence in their quote (AJ wanted to remove the quarter panel to repair the large dent and paint it, whereas Caliber gave me a quote for pulling the dent and painting it while still on the car).
I was paying out of pocket, but I went with AJ-USA despite the higher price since I had more confidence in their quote and their work.
I will say, though, that I don’t think much of after-market paint jobs. AJ’s work is warranted (by the paint system manufacturer, I believe) for 10 years. The work done in 2000 has had the clear coat bubbling and peeling in the last year or so. To be fair, we did not take very good cosmetic care of that car over the years (washing / waxing), so I don’t know how much to attribute the product life expectancy / warranty correlation vs. poor upkeep on our part.
That being said, based on our recent repair with them, I am certainly inclined to use them again, and I’ll try to take better care of the recent repair we had done with them.