Better yet, I never even use MD5 because the chance for collision is much higher than SHA1. I'd highly recommend not using MD5 for large databases and only using SHA1, at least until SQL Server supports a stronger hash.

It's fairly easy to calculate the risk for collision, and I recommend anyone attempting this approach make their own calculation, so at least they understand the risks of introducing inaccurate data.

Other than that, hashing techniques works great.