Gowdare.. I have heard this engine note funda for wayyyyy too long to say , it is BS.. On the turbodiesels, there is not enough rpm range for you to play with unless you are shifting close to redline.
The best driving experience is when you shift in a manner that when you upshift , you still are in the rpm where the turbo is still in boost. In the Scorpio you lose 600-800 rpm per upshift and the boost happens realistically about 1700rpm hence with a 2500 ~ 2800 rpm upshift you can definitely stay in the meat of the powerband with turbo on boost all the time. Healthier for the engine as it is getting all the air it needs and not having to cut fueling all the time.