Look, at the end of the day everyone takes their cars to a place that they trust.
1 thing that cannot be guaranteed is the workmanship of anyone on your car. The only way you are going to get good service is by customer loyalty. Find someone who knows what they are doing, and stay with them.
Me- I know Shaun @ Boostworx does know his stuff, and does a good job. I go back when i need to.Why? Because i know he wont fix bogus problems, doesnt fark around, and he doesnt charge like a wounded bull.
Asking people what problems they have had is fine, but dont take someones opinion of a workshop the final say. Just because they have great service, doesnt mean you will get the same.
ps - ive lost a motor due to someone overtightening a tensioner bearing. I wouldnt take my Turbo to be Tuned there