After throwing away that thing you will never use to creating filenames far beyond 8.3 format, the problem always comes soon after the matter is fully resolved:
I have a personal convention that all files I put into my synced folder must consist of lowercase alphanumeric characters, hyphens and periods (to be precise, match the regex /\.?([a-z0-9]([-.][a-z0-9])?)+/). It saves a lot of pain.
It can handle files with colon in the name fine, Finder just won't let you name them like that. The files themselves work fine if you created them in the Terminal/through sync.
Classic MacOS used colon as a path separator, so to support creating files that could be opened on classic MacOS the Finder disallows it.
Personal notes, and tons of academic papers and ebooks, all of which might contain question marks and colons. Occasionally, I also use arrows -> in travel itineraries / ticket PDFs.
Yes and who needs Dropbox since for a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.