I'll let you all know in awhile. I upgraded to a SS Guarantee 5 weeks ago. The sailing is in about 3 weeks and I still don't have a cabin assignment. When I booked there was only 1 Guarantee available and then about a week later they opened up Gty sales again for 10 days. At the time they had 3 CS, 5 RS and 1 PH open but they all disappeared when they opened up for Move-Up.
While I know I will get a cabin it is a pain that I can't order luggage tabs or print my boarding pass until I have a room assignment.