Thanks for starting this thread, Horace.
It is a question that has always inrigued me. I have known a few who came back - it was financially ruinous for them, yet they were releived to be 'home'.
I recently took my youngest for a look-see in the UK (I was born there). I realized that although it would be a great opportunity for her, and one I think she should take, even for a short period (12 - 24 months), I could not live there. As much as I love the place, and the fact that all my own family is there. Nah.