Well, Draftsight and SolidWorks are only compatible with the 2010 DWG format, so your AutoCAD 2013 and 2014 drawings will need to be saved back to the previous version. If your Plant design engineers are using Plantspace or Autodesk plant design, then going to draftsight is going to be a problem because of the API not being available in the free version and it's compatibility with AutoCAD being a dubious assumption.in the premium version, you may wind up pulling the rug out from under your plant and process people.
I just watched a demo on SMAP3D-which is a new add-on for SolidWorks for creating PNID, plant drawings. Maybe you could entice them with it.
From my understanding they are using either AutoCAD Mechanical part of the Product Design Suite Standard 2012\2013 or just the LT 2012\2013.
I have not heard of SMAP3D. I will check that out!
Thanks John, very much appreciated!