Faarn,
You have my deep sympathy as exactly the same happened to us in our previous overseas posting - cut from £45 pd to about £8 in a very short timeframe. Factor in loss of spousal earnings, higher mobile phone, internet, insurance and other costs, the financial equation doesn't add up. However, we had a great time, lived in an absolutely stunning part of the world and our kids became uber-brat skiers.
In my current appointment, we are on different TACOS and get a different package - yes, it is a lot more generous, but it just brings us up to what we were on in UK with my wife working in a good - but low paid - job. Again, a great experience, but loss of career time again for my wife.