I'm guessing that he sells you an SCT tuner with "his" custom tunes loaded into it. A couple of things to think about:
1. You've got a couple of tried and true options here, namely Bamachips and Brenspeed. I personally have a Brenspeed and can't say enough good about it and the outstanding service that I have received from Brent.
2. You didn't mention f any mods have been done to your car, or if any are planned. Might be that if you're going to mod the car and your local guy is going to do the mods, his tuner might be the way to go. Does he have his own dyno at his shop?
If it were me I think I would at least talk at length with your local guy and more importantly, some of his customers, before making a final decision. I'd be interesting in hearing what makes his tunes different or better than the two I've mentioned.