Re: Has anyone used Chip Express tuner?
I don't know. I might keep it and reinstall it if I were in your position. While I AM one of the guys in the bluespark thread questioning the integrity of those who would remove mods before taking a vehicle in for warranty work, you have essentially already done so.
With that being said up front, I'm with your diesel mechanic friend that if you leave it at stock/mild settings you're not likely to be doing unsustainable damage. Will it shorten the life of the engine/powertrain? Probably not appreciably, but that in part depends on how often you enjoy it.
The thing is, many manufacturers hold back a little in early years of a model generation so they can claim more horsepower/torque on later model years to sell newer "improved" vehicles to repeat customers. The easiest way to hold back some of that hp/tq is in the tune.
Odds are you're just fine with a mild tune. If you're worried about this voiding your warranty, it's too late anyway.
Eventual owner of '15 WK2 Limited EcoDiesel. Currently stationed overseas.