@hrtrob Sorry, I missed your direct message from 2 weeks ago. I just replied and shared my experience with you. =)
For those who might want to know, I received a new replacement DD+ base and I've returned my original base for FANATEC's analysis. In short, the new replacement base is awesome! No coil whine and most importantly, for me at least, there is no "grainy" sandpaper feel when the wheel is turned left or right! The replacement base is truly butter smooth! The base firmware that came with it is from PC Driver 455 (2.0.1.4) and the WQR firmware is the test hot fix (1.1.0.3) that Fanatec had volunteer’s test. They had to have loaded it from their German headquarters knowing that combo firmware is the most stable at present. The firmware from PC driver 457 and the test WQR "hot fix" resulted in my original base developing the "soft disconnect" issue, which seems to have perplexed their software/hardware engineers. I suspect there's a batch of bases that have an out of spec internal component that is not playing nice. Anyway, glad to have the replacement. It's been a true joy to play with for the last couple of days.