If I were you, first I will see whether your daughter can catch up the standard of SF since they are quite tough and the workload are very heavy. if you think your one is capable to catch up, I will agree to change it because TNS secondary school is not very top but only medium level but if you choose SF, you can choose Holy Trinity or even better secondary school. (Depends on the academic result of your daughter).
In my opinion, I will choose a better school although my children cannot rank top in it rather than a fair school but rank top in it.
Most important is too evaluate your own kids and find one that suitable for him/ her