Certainly the Principle in Zhengzhou is right to say that 16000RMB a month is more than what the average Chinese family in Zhengzhou would make but then i don't believe that the average Westerner would be happy living the average Chinese lifestyle. 1000RMB is not going to cover the price of a nice apartment suitable for 4 people. You'll be spending around a third of your total salary on housing your family in a modern apartment, then if you decide to send your kids into private education it's going to cost you a reasonable sum of money.

I've been to Zhengzhou several types and haven't noticed that the air pollution is particularly bad just the same as most larger cities. Still in the winter your more likely to get sick and the summer you probably won't see a blue sky for a couple of months. There doesn't seem a great deal to do and see in Zhengzhou itself, it's mainly just a business and transport hub for the province.

Macau is going to be more expensive to live in than Zhengzhou (I've not lived there myself but have visited it twice). However, if they are offering you an apartment and schooling for your children then it sounds like a better deal IMHO. Also Macau is probably going to be less of a culture shock than living on the mainland - more English speakers, better services, better lifestyle in general.