One of the very few remaining reasons why I don't go all "Ticci" and do all of my writing on the iPad is that when I'm writing books for traditional publishers, they have a tendency to get queasy with anything that isn't written in Microsoft Word. Since they also like to keep an eye on what changes authors are making to documents, change tracking has to be turned on in Word all the time. So in the past, the vast majority of my offline writing has been done in Word on a Mac just to keep those publishers happy.
Not any more. Through a happy experiment this morning, I found that Pages (for both Mac and iOS) now does a much better job of round-tripping with Word. That's the term for shifting a document