Not long after I got my new iMac TTP had reported an initially unknown S.M.A.R.T. value as out of range, but DU said the drive passed S.M.A.R.T. With the help of Google I was able to find the unknown S.M.A.R.T. value was heat related. I contacted Western Digital and they said no third party utility was capable of accurately interpreting their S.M.A.R.T. readings. A few weeks after that the drive failed completely and had to be replaced under warranty. The day before the failure TTP was still reporting and out of range S.M.A.R.T. value and DU was still insisting that S.M.A.R.T. was "verified".
Personally I will take TTP's word from now on. The problem is convincing Apple and/or the drive manufacturer to accept it as well.
