One company we worked for, lost two or free good US developers (lost because post-acquisition earnout period ended for them and they never intended to stay for longer, as i understood), and hired a Vietnamese company. Then they realised it wasn't going well and hired us (Cyprus+Ukraine) company to fix. Then they had to lay off almost all of the remaining US team and nearly went out of business. Not sure which one of the contractors ruined them :D but in any case it didn't go well - they'd better stick with US people.

As an outsourcer with 25-year experience, i think outsourcing is always a bad idea and even desire to turn to it says that something in the company is seriously rotten and it will probably head south pretty soon anyway. It just doesn't work because objectively incentives for outsourcer - whether individual contractor or a company - in fact individual contractor is a lot worse, unlike normally believed - are fundamentally misaligned with those of the client. For a full-time employee with job security and stocks, they can be more or less aligned.

I spent 4 years living around Saigon, and got to know a lot of the tech expats in the community there.

As always, depends on the company you deal with. Some can be shady, some not.

Vietnamese culture is fascinating and lovely, they work super hard and there are a ton of really smart engineers there. But they also do things a bit differently and it'll all gel depending on how westernized they are in their thinking.

CodeLink and EastAgile are the two companies I'd work with. I know the founders personally as business and as friends. Really solid great people.

You should definitely work a deal with your company to go visit.