As with any remap of a vehicle, it has the potential to highlight any current issues and will put increased wear on the drivetrain. As such, it's important to properly keep the engine maintained.
That being said, I have remapped my 1.4Tsi ACT, and got 176bhp and 225ft/lb or torque. It drives lovely and the power delivery is smooth. There is a marked difference from before the remap.