Probably the biggest issue for anyone considering moving to HKG is schooling.
Getting kids into a decent school can be difficult and very expensive. This is not just an issue for expats, since most locals are just as keen to get their kids into the same schools.
So, if you are considering bringing your kids to HKG, or starting a family soon after moving here, then you need to plan your finances accordingly.
One reason that DB is generally more expensive than TC is that there are more options for education for non Cantonese speaking kids.