I was at one of their open houses a while back when Steve Dinan was there and fielding questions. He's obviously very knowledgeable and pretty funny as well. I personally enjoyed his answers and feedback and he seems like a nice guy. However, there were those in attendance who saw him as someone that loves to hear himself talk.
It's worth dropping in if you're nearby. AtSpeed has a nice shop full of serious machines.
They are located in Hanover, MD., not far from BWI airport.