Well there is a body of childhood development work which says that stability is good for children. One of the bad effects of poverty is childhood chaos....or vice versa maybe. So yes, moving them to a strange country and dumping them in a bad school might be worrying.
But perhaps something I use for my own justification in taking the plunge with a small child...I do believe that children are very resilient, and that if you have a strong family unit, one where the kids feel safe and secure, then a move can be good; they will understand that even with great change, the family functions well.
I mean we lived without furniture for a couple of months here, and while it did my back no favours, my daughter didn't seem to mind at all.....she had her laptop. But there is quite a bit of second guessing.