One week with the replacement SB3 and so far there have been no issues whatsoever. I use it extensively each day, while connected to my Dock v2.
One thing I noticed is that the new SB3 does not show the performance slider when clicking on the battery tray icon - my old SB3 did. The new SB3 also has a “Balanced” and “High Performance” power plan, whereas the old SB3 only showed “Balanced”. I’m convinced Microsoft made some sort of firmware or hardware change that is reflected in the replacement unit.