I just did three segments in C on SQ. On each segment, I had BTC. I was glad I did, I liked what I booked better than what was offered on the menu. HOWEVER, as part of the pre departure service, I was asked on most segments whether I wanted to keep what I booked, or order from the menu. So book what you like, and don't hesitate to order something different on board. If possible, they will be more than accomodating.