"Everything else being equal, you'd go where the approval process is easier," said Wang.

Empty nests and angel money

For some, coming home is as much a personal as professional issue. Many are 'empty nesters' whose own children are now at college, or they have ageing parents.

"In the US, people have family and friends who can support them with 'angel money.' As first-generation immigrants, we don't have that kind of access there," said Zhang at J&J Innovation.

For the returnees, it's just the beginning.

"We've planted the seed for a fast-growing, innovation driven environment in China," said Steve Yang, chief operating officer at WuXi AppTec. "The impact of this group will be better measured in another 10-20 years."