The main hurdle is really experience (I am <5yr) and family (my parents are aging and may need my intervention in fewer years than I think). Firms usually only hire internationally for skilled engineers and there's no guarantee my accredited degree from the US is valid anywhere else. And if I went someplace other than Canada, the travel costs would likely result in me only coming back to see the rest of my family once every two years, which sucks and could pose actual problems.
Don't get me wrong, I honestly do like the idea of going someplace with real human rights, but unless it becomes clear there is actually a threat to my existence I can't justify that big of a change. I love my family too much.