Not that it would make a huge difference to you all but from an Information Technology standpoint the Mitchell product is a true PIA. Very crappy to install, difficult to manage and update, and then they turned around a stopped supporting one of the products we purchased and wanted to force us to pay to move to a similar line.
The All Data solution we use now is the online version and I have heard good things from the garage on it. They still use Mitchell for some information but All Data seems to be easier to use and is much easier for my department to support.
Just 2 cents from another viewpoint.