Great job with 6.0 beta 1... it's great to see it move out of the alpha stage!
Huge thank-yous for the database management tools under Tools -> Advanced, too.
One thing, though -- I'd love to see the Overall Rating field be customizable. I've long had my own rating field that's had between 0 and 5 stars in half-star increments. I'd like to move that to the Overall Rating field and be able to change it in the future, if I want to.
Great job, Andrei. OCD is still by far the best music cataloging software out there.