I have measured it myself within my organization, and I know many peers across companies who have done the same. No, I cannot share the data (I wish I could, truly), but I expect that we will begin to see many of these types of studies emerge before long.

The tools are absolutely useful, but they need to be applied in the right places and they are decided not a silver bullet or general-purpose software engineering tool in the manner that they're being billed at present. We still use them despite our finding, but we use them judiciously and where they actually help.