I got about the same result from installing/tuning a safc2. 170 up to 181kw, same mods as you on stock ecu.
Main difference was comes on quicker and smoother after 4k rpm.
I think biggest benefit of the nistune is now you can do more mods for more power. (increase boost, bigger turbo, etc) none of this can be done on stock.
Mods = more power increase
ecu = how well you can use the mods.