Do you have the list of 500 secondary schools joining such vivo miles scheme and what are their rankings?
Personally, I think that sending children to UK is still worthwhile especially for joining those high ranking schools with the following characteristics commonly found in those top notch schools:
-Excellent discipline - students would not be allowed admitting to class even if late for 1 second and must turn off lights after 10:30 pm.
-Updated information for parents - parents would be well informed even if your kid does not concentrate on class.
-Heavy workload - at least over 2 hours daily homework which would ensure the rankings of schools above par with the national standard.
-Daily sporting - 1 to 2 hours sportings like hockey from Monday to Saturday to keep your kid very fit.
-Small class size - about 15 students per class.
-Variety of foreign language choice - students would be required to learn at least one foreign language for GCE.
I think HK schools can hardly offer small class size, compulsory daily PE exercise, early sleeping and above all the exposure to foreign culture.
Lets just say that you have to differciate between grammar state school and state school. Normal state school can't choose who they admit so you'll get mix abilities, Grammar and private all have entrance exam so they only admit students which fit their level of learning. Thats why state school don't do as well, as students are too diverse in their abilities.