Had mine done last week. For me it is a complete fix! It makes the ride smother in all speeds not only the dredded 1300rpm spot. I am not able to force the problem either. I had a tad of vibration running motorway speeds around 130-140km/h but that has dissapeared too. Thought i had unbalanced wheels but that was not the case then. It also make the idle rpm lower and they have deleted the old software fix that made the engine try to skip 1300-1400 rpm all the time. You are now able to easily choose to stay on 1400 again.
It feels som much better and more luxurious with a smooth drivetrain !