I've met several Hmong over the years. Every one of them has been a stright up person - albeit with an unusual sense of humor (yes, actually all of them). All of them have also been very patriotic Americans.
As an aside, those that were in Vietnam and did not come to the United States were largely killed off. Lost I heard, more of the Hmong now live in the U.S. than in SE Asia - though the numbers in China are not well known.
I think you mean Laos, not Vietnam. There are still a lot of Hmong in Laos. The ones that were killed were the ones that were allied with the US during the Vietnam War. Everywhere you go in Northern Laos you will see Hmong. It is impossible not to see them.