I'm in Austin but haven't had to take my Crossfire to anyone for anything except the yearly inspection. I'm trying to do everything on it myself. I've had my Crossfire for three years.
I've talked to the guys at Austin Auto Techs about future help and they are willing. I've used them for all of my other vehicles for over 15 years. Very honest. The same guys have been there the entire time. They aren't dedicated Mercedes mechanics, but they're willing to listen to what you think needs to be done and will work with you. You can talk/email to Mike or Hugh or Brian. Austin Auto Techs Auto Repair Texas I don't know how good they would be about diagnosing some of the obscure/difficult things on the Crossfire. But if you do the majority of the diagnosing and point them to it, they might be able to do the heavy work for you.

Please let me know if you find someone close to Austin who knows as much as the folks here on this forum about the Crossfire!