vimwiki + dropbox user here too. I was a big time OneNote user until I needed my notes on all the major platforms at once. I realized that I would much rather keep them in a text-based format, rather than in a proprietary encoding with no API, even though I think OneNote is a fantastic tool.

So far it's worked fine for me, even though I wish it supported Markdown out of the box (there's a plugin for it somewhere), rather thank its custom markup. It's somewhat painful to have to remember yet another syntax to achieve the same exact thing.