We are also booked on a Cat. B guarantee for the 9/27/3 sailing. We've used the guarantee format for most of our cruises, and have always been satisfied. Most of the time it will be in the category you booked, but once in a while you get bumped up. On several cruises our docs said "TBA" and we didn't know what we had till the luggage was checked. Then we opened the brochure to find our cabin for the first time.
All part of the adventure of cruising for us!
Mark T.