i know a couple Spring pilots and it is currently a good Jub plus you get to live in Shanghai which is a great deal.BUT!!!!!!!
Most of the guys I work with had the choice to apply to them or BCA. To a man, we all chose BCA, not because we thought it was better, but we didn't want to be held prisoner to a gigantic bonus at the end. At the time Spring paid 10% more, but not until the end with all the bonus money.
Fast forward 2 years. so far Spring has met their comitments. But working in China is a month to month gig. you never know when you will fail something, even for no reason and no fault. I would make the same choice again, even though I would prefer to live in Shanghai. I simply don't trust the locals to keep their promises,
The last I heard Spring is still a decent place to work, but having a 74,000 dollar rope wrapped around my neck for 3 years isn't worth it.
Everybody gets to make their own choice.
My humble opinion.
Other opinions may differ.