You know most (not all) will blame the tune and not cover it. I've seen it happen a lot on forums, for myself and other friends. And these have been simple things from alternators to spark plugs to transmissions. So with anything, you still gamble when it comes to the warranty. They could say that you uploaded the revised tune wrong. And do you think they will show you any results from their tests? No. But like I said, there are dealerships that will help and fix the issue.
I've heard good reviews on the cal but once they go with a actual tuner, they usually report better results.