Miguli - Let me address some of your points.
Age 39 - I hate to say this but you may be getting a little long in the tooth although with the rate of take up at this level, the desperate may be willing to accept the desperate. Sorry to put it like that.
HK - It's a great city....... to visit. It's a great city in which to live....... if you can afford it. I don't know what your wife does, but unless it's a significant earner, in region of +40k/mth. You will be in the red each month. Take into account you will have periods of time off as an SO where you may want to travel. If your wife is 9-5'ing, she will not be joining you on those travels much. Usual leave allowance in HK offices is 10 days/yr.
Kids - As you are male, CX probably doesn't care, as i expect with other airlines. Probably a small upside because you'll be even cheaper for them to hire.
737NG - Why? Who are you applying to? Only HK Airlines flies them as a HK carrier. If you're applying to them, imagine may be a plus. If you're shooting for any other carrier, save your money. You're going to need it.
Social Life - Way to enter mid-life. Sounds like fun.... As an SO, you are a cruise pilot and radio operator. Even in the cruise you will always be PNF. Stick time = 0hrs. The novelty wears off very quickly and you will miss your Seminole like your first love.
Bottom Line - Yep it's more money but that's not your priority. Who knows, it may not be more money when the wash is done. Fair call, your options are limited at this stage. I still think you're selling out all your work to date for a very cheap price and do believe you will experience a pretty poor lifestyle in HK. It's a real pressure cooker and can't believe that there are not better, more respectful packages available to you. Corporate perhaps?