I've been to both Dr Lam (HK prenatal diagnosis center) and Dr Patrick Chan and I would have to say that a) Dr Lam is great if you want very high quality scans, but not much in the way of other prenatal care/pregnancy advice etc - and b) Dr Chan is great if you want someone to look after you through your pregnancy even though you will not deliver with him. Overall, I recommend Dr Patrick Chan for that situation. He's a fantastic doctor. Although I'm going to have to stop recommending him so much because it seems like more and more people are seeing him these days - I don't want him to get overcrowded or more expensive as he gets more popular!
(I too was dumped by a doctor, Dr Phillip Ho in my case, when I told him I wanted to deliver at QMH. Dr Chan on the other hand asked me about all my test dates in the public system and whether I would prefer them to be done by him or the public system. He worked WITH the public system instead of against it.)