I have not and just used it as an example since it was one of the first places I thought of when I mentioned density (along with Mumbai). But I have been to Seoul and lived in South Korea for a year. I had Hong Kong on my list of places to go see... too bad what happened.

I absolutely agree with you that Hong Kong from an infrastructure perspective has a lot going for it, but I think that skyscrapers are an anti-pattern. You can't repair them yourself, they require specialized knowledge to create and support, extremely dense environments are breeding grounds for contagious disease (this is a general statement), and from a natural standpoint they're quite sterile (the parks, while great, are illusions of nature - a toy or a simulation). I think we'll also find that skyscrapers cause anxiety and depression here in the near future as/if research is conducted. You also require massive infrastructure for cities, again more specialization. They're very much reliant on cheap fossil fuels to create and support, even if they're per-capita lower on emissions. If we run out of oil and I live in a 30,000 person city in Europe, life goes on. I still walk like I was before and farmers still bring their goods to the local market. If we run out of oil and I live in Hong Kong the entire thing crumbles to bits.