after the SIXGA website design discussion meeting (in Apr 2008 ?) attended by 卷心菜, he mentioned that 新加坡等级分 is not likely to continue due to (not much data to support the computation ?).
As you suggest here about 新加坡等级分, I just include the Malaysia system here for those who like to think about this issue.
relevant or not is for those who wish to study those issues mentioned by you. :)