My elder son was graduated from SC and my younger son is now studying in MS. Last year, I chose MS and gave up SC (and KV, LH, Soka..etc) -not an easy decision.
The main reason is that I want a "secured P1 place" in a good (though not top) primary school. It was a nightmare to play the P1 allocation game and surely the competition is more keen 2 years later. Another reason is that the saved school fee (MS's school fee is one tenth of SC's after deducting the gov. voucher) can be paid to some private NET lessons.
Both schools are good. SC is a happy school and kids are quite free. There is no dictation nor exam. My elder son took some times to adapt to the primary school life. MS is very traditional. The school has improved a lot in English and PTH standard in these years. They have NET lesson 4 times a week.