The supply of Tung Chung's flat units will still be in high side. When there is a downturn of property price, it's price will drop more severely. Suggest you to sell it and turn to Kowloon when the price is still high. Also, it is also a good preparation for your child to enter better kinder and primary school.
Please take care of renting a house after, the mortgage rate will stop rising commencing after 1-2 times increase of rate in the first quarter of 2006. The property price will rise then.