Irrational exuberance at joining
If you were like me you skimmed over the CoS when you were joining. I remember thinking 'cool, when I have kid CX pays 90% of the cost'. Anyone joining in the last 10 years would have thought their dependants were covered for medical.
Reality
Most schools available in HKG cost far more than the ESF rate. CX did improve schooling allowance in 2001 to cover 75% of the higher amount. But since it is taxed you actually get 2/3rds covered for schooling equivalent to free schooling back home.
Your dependant cover is so low that any emergency operation etc will cost you a small fortune as many have found out the hard way. So now you need to top up the CX cover.
So new joiners, Caveat Emptor!