Marc - I suspect it depends on how you look at it. Since I could have received ANY leftover cat F that was available, my D cabin location (starboard and midway down the forward hall) is certainly not bad. Seas have been calm, haven't experienced any undue vibration/rolling/swaying. I would have been happy with any balcony given the savings that we had on the booking but very happy with our actual cabin. As to whether there truly is any advantage (or should that be DISadvantage?) to cat D versus cat F is left to the reader as an exercise. :D

Technically, yes it is an upgrade. But I also understand your point, Marc.

Masaki