I\'ve been playing around with git and hg lately and then suddenly it occurred to me that this kind of thing will be great for documents.
git
hg
I\'ve
You can use Beyond Compare as external diff tool for hg. Add to/change your user mercurial.ini as:
[extdiff] cmd.vdiff = c:/path/to/BCompare.exe
Then get Beyond Compare file viewer rule for docx.
Now you should be able to compare two versions of docx in Beyond Compare.