Barry,
If Everything works on OSX 10.9.5 i would use that awhile longer since moving OS is a surefire way to get problems with PT.
I haven't hear anyone complain about PT11 on macPS Sierra but i would stay put if it works and but a used Mac with Sierra if you really "need" Office16
All in my opinion of course but i would stay put on Mavericks because it is soo Darn Awesome for PT
