So if I've understood correctly:
You will be making a better than HK salary in a city where apartments and food cost much less. Seems like a smart move to me. My biggest gripe with here is the lack of food hygiene. Its not hot enough for places to bother with refrigerators, it seems, so food is left sitting out all day, slowly going bad. I've had (probable - can't know for sure) food poisoning 4 times in 3 months. As HF said the pollution isn't bad compared with most Chinese cities, but it is dusty from the continual construction.
Very strongly suggest you come and take a look before you do anything.
I'm surprised that nobody has mentioned the difference in weather. Clothing that is suitable for winter in Hong Kong might do well in the summer here. Warmer clothing is needed for winter.
And speaking of clothing, if you wear larger sizes - good luck. I can't find shoes or even underwear in Kunming that fits. The last time I needed shoes I went to Hong Kong!
Yes the weather is much cooler and less humid than HK.
Yep, live in Kunming for a couple of weeks at least to understand the place. Very, very different to HK and you will realise there is a lot in HK that you miss. Many Kunming expats "escape" to Hong Kong often so they can go to a place where things work, people aren't mostly farmers and where stuff actually happens! Kunming is a backwater Chinese city, nothing like East coast cities, if that is what you are using to compare.
Then again, Kunming is much quieter, less busy and has about the best climate and outdoor/adventure travel options of any large Chinese city. With it becoming more and more accessible by the year, the backwater name tag might not last too much longer. But in terms of local oppourtunities, there are basically zero service industries around, so if you are a manager/IT/finance person etc, work oppourtunities are non existent. Your only option is English teaching or buying your own already operating business.
Hong Kong and Kunming are very different, but don't listen to the nattering naybobs of negativity. Kunming is a great place, and if you already have a career or business that you can practice here, do it.
Also, the suppose "food safety" issue is not what some very negative, paranoid foreigners make it out to be. Millions of people eat local food every single day, and they live perfectly normal, healthy lives. I buy meat all the time that was slaughtered that morning and has been sitting out all day, and I have yet to have a single problem with it. It is usually delicious and perfectly healthy.
food poisoning IS an issue here.
nailer, it is not the issue that many angry foreigners make it out to be. If it were, then most people in Kunming would be constantly, deathly sick, vomiting and spewing other things all over the streets every day. But is that what we see? Cooking food kills bacteria.
I've had serious food poisoning (fever, pains all over my body, diarrhea every 20mins for 24hrs, ill for a week) 4 times since ive been in kunming. Plus many milder bouts of diarrhea, running to toilet etc.
I consider that an issue but maybe some people dont.