Sounds like your reasons for moving to Chengdu revolve around ex-pat community, night life, housing, restaurants, weather - basically entertainment value.
EXPAT COMMUNITY
Most definitely larger than Kunming
NIGHT LIFE
More happening than Kundu - and Chengdu is larger so LOTS more eye candy.
HOUSING
Depends on where you want to live. Most cities look the same - so new stuff is the same in most cities - old stuff...the same. But there's Chengdu has higher density population so things will be a little (aka a LOT) more crowded. Simple things such as catching trains, buses, airplanes - PAINFUL.
RESTAURANTS
Same - but they don't have a Salvadors. Really - I've eaten at most Mexican-style restaurants in Beijing and Salvadors - although not "true LA-style Mexican" - plays a good second fiddle - ESPECIALLY for China.
WEATHER
Can't beat Kunming (or better still - Anning, Dali, etc).
ECONOMICS
You left this out but I thought I'd chuck it in FYI since you're NOT Bill Gates, Forbes, etc. The GDP per capita for Chengdu is about ¥35k, Kunming is about ¥28k. You should expect things to be more expensive than Kunming. Chengdu is a HEAVY recipient of government financing over the last 10+ years as China tries to improve the economic standards in the west.
Gaoxing aside (dude, you're famous), most long-term expats love it here because of the weather and it's so economical - culture issues aside.
CULTURE
You left this out also - but again...Chengdu is quite similar to Kunming in that the locals blubber Sichuan Hua (local dialect). Incredibly tough for me to understand - although I have noted it's a FANTASTIC language for cussing something out...you can take the culture comments from there...
Chengdu - as in Kunming - is far from Beijing. You should expect some political and governmental anomalies. The government recently smashed (and executed) a very large corruption-based criminal organization. Where there's one cockroach....so just be careful as usual.