In Raffles they usually don't let you have a second main course, execept of course when its pretty empty. I was one of two people on the lower deck of a 744 (SQ 231 SIN-SYD) and the FA's were more than happy to offer me a second main, but having eaten before the flight I declined.
I tried the Chicken Rice from BTC Raffles Class and it was rather dissapointing because the chicken had dried out, but otherwise it was fine. I guess if there is something that catches your fancy on the BTC menu, then go for it, otherwise SQ meal selections are usually very good. Either way, you won't be going hungry
Coathanger