Definietly consider the ESF schools. I've been quite pleased with them. If you move to Beacon Heights, the Beacon Hill School is right next door.

The schools are structured P1-P6 (P-1 = kindergarten in USA) and then secondary schools go Year-1 -> Year 7 (the equivalent of 6th grade to 13th grade). Most ESF schools are now switching over to the IB (International Baucalaureate) which is very transferable. But, if you are only staying in HK for 5 years, then your children will only be starting 9th grade or 10th grade, so they'll do fine.

The only slight issue is that they will learn British spelling (my daughter was told it is GREY not GRAY). But that is no big deal in our international world.