Two things I need to address separately here.
1. SOB- you are right and wrong. The tuner will tweak several ( maybe even several hundred) parameters of a tune. They are not able to tweak all of the parameters. Therefore, when someone tunes a car with the GMPP tune, some or most of the GMPP tune will remain. If the tuner uses the stock tune to tune from (assuming the owner of the car has the file) then the above will not be the case, as the GMPP tune parameters will not be in the ECM.
2. Miller-
While you and I have had a scratchy relationship, mostly in fun, I can not stand by and have you calling out a product the way you did. You state to the OP to avoid a trifecta tune and go on to suggest that trifecta tunes lead to engine failures. In your next post, you admit to having absolutely no factual data to back it up.
Think of it like this:
Hey everybody, don't ever buy a Cub Cadet Tank because the blades come off and will chop off the head of your neighbors dog if you don't use 89 Octane. Instead, look at Toro or John Deere.
Just an absolutely ridiculous statement that is completely unfounded, potentially damaging to the reputation of the company and not based in reality. Unacceptable.
GJ