I think it's the best out there, but it still needs work. ChronoSync hangs on large (even successful) syncs - for me, 10,000+ files. Every time.

Also, it doesn't recognize overwriting a folder and a file of the same name, won't allow a user to rename files or folders from within ChronoSync and then refresh, some other drawbacks. Many features that were available in my old favorite, PowerMerge (development ended long before OS X) would do well to be incorporated in this package.