i have seen some of these facilities at various locations (not in central america). Some are very good. Obviously you will get more experience in a long established US operator, but the reality of todays world is that airlines will explore any way of keeping costs down.
To us drivers this may seem like a risky venture. But to a bean counter, well quite frankly, if an engineering department finds a "good quality" MRO in a "third world" country then the maintenance is either "done" or "not done" to the companys FAA approvd standards. i.e. the bean counter will look at safe or unsafe. Not various shades of it. If the standards of your own airlines maintenance are deemed safe, the argument is "how do you get safer than safe?" So if this third world MRO meets the standards and it's cheaper then it's a no brainer.
This is an interesting discussion I have had before and there is no real answer, but it's a discussion worth having!