I want to knock on wood before I say the following.
We have just come off a period of 21 days of heavy use of WL 9.0.25 (9 to 5 - 7 days a week) . It has been a joy to work with. The only problem with it during the 21 days was when we installed the latest update WL erased all our preferences but they were easy to put back. I love the new “black” UI and so do our clients. I could not be happier… now if it just keeps working as well as it has it will be the best Wavelab ever, IMHO.