Quickly thinking out aloud.

A probable rule of thumb, if you are not of mixed heritage, do not migrate, stay where the many generations of your ancestors have lived.

If you are of mixed heritage, maybe then that genetic test may do significantly better than any other rule of thumb.

A gene test for determining susceptibility to AMS was being worked on in 2011: http://online.wsj.com/news/articles/SB1000142405274870336290...

There are probably other loci that provide selective advantage to, in this case, higher altitudes. Without having a rolodex of those, it would be a challenge/highly unlikely to predict phenotypic advantage.