It's quite pity for kid to suit the different environment within a short time, like living area, from K3 to P1, transportation, more & more homework and activities ...
About the money terms, let say 4mil home, the transaction fee (stamp+agent+solicitor) is already 5%. If sell the original and buy a new flat in area close to the school, then it involves already 0.4mil. Not counting the decoration fee and removal fee. It is not easy as Hong Kong parents.
But that is a problem if you like living in the old home, environment. So you need to sacrifice to a new living environment that might not be good for living.
This depends on how you "weight" between the living environment and the studying enviroment/schools.
For me, better schools is more important.
I am currently renting an apartment in net 14, but my son is only studying in N1. I may consider to move and rent an appartment in net 12 when he goes to K2, in order to have a higher chance to get into a good school in net 12 during "lucky draw".