We just got off the Silhouette (on Monday) after a nice 12 day cruise and wanted to update my prior post. We had an AQ cabin and were assigned to Blu. When we arrived in our cabin (on embarkation day) there was a letter telling us we were assigned to Blu and that Blu now had "Open Sitting" from 6:00 (might have been 5:30) to 9:30. The letter also said "our reservation was confirmed for 8:30" that first night. It turned out that we could have showed-up anytime that first night (we went at 8). We never made reservations in Blu (you can do this) and were always seated immediately whenever we pleased. As to eating in the MDR...this was a bit of a hassle. One evening we did not like the menu options in Blu and decided to go to the MDR (they had a great menu that night). We went to the Select line at about 8 and were told that "you are assigned to Blu and cannot dine in the MDR as a Select diner." The maitre d said we would go down to Deck 3 (port side) at 8:30 and get an assigned table. At this point we decided to go back up to Blu where we knew the Blu maitre d. We told him we wanted to dine in the MDR that night and he immediately telephoned the MDR maitre d. We finally reported to the Deck 3 port entrance to the MDR at 8:30 and had to wait to speak with the maitre d who then told a staff member to take us to 2 different tables to see if there were any open seats (the first one had seats). So, in the end we did eat in the MDR and it was a great meal. The table and the waiter ask if we wanted to keep dining at their table but we did return to Blu and other alternative restaurants for the remainder of the cruise.
One other Blu story. A friend of ours happened to be waiting to get into Blu because a couple, who had booked the largest most expensive suite on the ship (the Penthouse Suite), was arguing with the maitre d. It seemed these suite passengers thought they could just show-up at Blu and be seated but the maitre d said he did not have any room that night and they should call in advance for reservations. These passengers were pretty annoyed and pointed out that they had paid over $23,000 for their suite but the maitre d held his ground