Sorry, I just happened by the forum, don't get here much. I live near Albany. DeNooyer is OK, but they were overcharging for them back when I bought my 2009 in 2011. I ended up buying mine from Summit Chevy in Auburn, NY.
Still, they're an OK dealer--just don't care for their prices.
As for local mechanic--Broadway Auto in Albany would be the place to go.
Obviously, this post was a while ago, and hopefully you landed your G8 by now, but posting this in case anyone else is looking for this info too.