My sister and I are good examples of what can happen to TCKs. I really thrived in the international schools we were in, made lots of friends and was generally very happy. Her experience was the exact opposite. She's three years older than me. When we moved to the UK so she could attend University, she thrived and I went downhill rapidly, to the point where I nearly quit school all together. The UK was a hard move for me and I never felt at home there. I still think my parents did the right thing taking us with them. We both got a lot from it, and though my sister struggled more than me, I think she would say she had some good experiences. A two year contract is not long in the grand scheme of things. Go, try it out, see how the kids fair, and if it doesn't work, go back to the UK.