Well, been there twice for open house type stuff. They had some bad ass cars on display. And there was a dude with a ZL1 there that they had done, he had 670 RWHP, but they were about to add some stuff and projected north of 700.
Mostly friendly, very informative, I had a nice conversation with the manager and they had a price list of "packages" for the LSA. It seemed like a good shop given that I haven't been to any others, but I let them throw my car up on the dyno for fun, with Rotofab CAI an no tune I've got 515RWHP, well that was before my headers anyway.
I know I didn't really answer the question, but hope it helps.
Here's my other take on it, the guy with the ZL1 they had done really had wonderful things to say about them, and they've done a ton of Vette's, Camaros, and CTS-V's, his statement was "They are the best in the Atlanta area." My instant response(in my head) was that for that kind of money I didn't want to best in the area, I want the best in the country. But if they are close and you don't want to have to ship your car and what not, I think they are a great choice. This time of year they said turn around time would be about a week. If you wait until winter they get backed up and you might have to make an appointment two months out or something, you know, everyone wants there car right now, wait til the crappy weather gets here to put it in the shop.