Hi Talli,
Those are good questions. Rest assured, aD does still build its own tools with ACS and use them extensively. WimpyPoint, Intranet, ACS Repository, Room Reservations, etc. However, to *only* use internal tools would be a classic example of 'Not Invented Here' syndrome. Not being involved with the Exchange Server discussions, I can't comment about that particular case, but yes, we do have faith in ACS.