I am an engineering director and I use the 12.9" iPad pro to review documents, create and edit office documents (PPTs/excel/etc), email, skype meetings, etc.
Office 365 is great on the new iPad pro. This week I had PowerPoint on one pane (70%), sharepoint on the other pane (30%), and mail as a slide over. I was able to create all the speaker notes for 5 different training modules we are deploying, which included copying pictures and text from the sharepoint site and my own speaker notes from email into the files.
OneDrive -> PPT -> OneDrive... no file system needed.
Laying out PPT slides with my finger is so much more satisfying than using a mouse to move graphics around!