I know someone with a daughter who moved there as part of the gifted programme. The girls in her class are extremely competitive to the extent that they will deliberately sabotage other people in order to top the class. For many of them anything less than perfect marks is a disaster and the pressure on them from the teachers & the parents is very high. If your children can handle that kind of environment they will do well and get a good education, if not they will hate every minute of it.
I studied at raffles from 1992-1997. I didn't encounter anything like you had described, but I wasn't in the gifted programme.