Earlier I wrote about the demise of MDT and yet saw it still advertised on Adesk's website. However I now understand my confusion. There are two products here. MDT was a 3D product that made it to the 2009 versions but is now no longer available. For a while it was only packaged with Inventor so that users could move across gradually. AutoCAD mechanical is a 2D and probably uses contraints and dynamic blocks etc to assemble drawings. An explanation is on this NG entry. and news here.
Sorry for any confusion. I thought MDT became AM just like ADT become ACA.
So bottom line is that MDT is now gone - but it did take a while longer than Adesk anticipated (at least publicly). It's already financially attractive to move over to Revit from ACA and I expect as time goes on that they will make it even more attractive to move over so if you are happy with ACA then stick around. There will be better offers on the table.
Bottom line for me is that ACA is performing well in our office. The newbie is catching on to ACA well (admittedly he's not your normal 'which Icon do I press' kind a guy and is happy for me to customise him) and we won't be moving any time soon (if at all). My multi level in one file approach works well (heck even Dragonfly can do it!) and the process and system is streamlined. A salesman (ex designer) is trying to get me to move to ArchiCAD which is big here but I want to earn not learn. I've spent long hours learning 'how' in ACA and now am enjoying the productivity of knowing a product well. Why would I want to start all over again? (Well for one ArchiCAD's Building Model Explorer is an awsome tool and cane's the pathetic Design Review or Navisworks into the dust for touring a building). But that aside I'm sticking with ACA.