Scott,
Running multiple versions of multiple CAD apps we already have a battle sometimes with the compatibility matrix. This is what determines when we upgrade and what we upgrade to.
The main concern for us is not to compound this issue by adding compatibility of MS office into the mix. For us this means O365 support across a broad range of Windchill versions is much more important than broader O365 functionality supported on limited Windchill releases.
Regards
Darren