arRsync is exactly what you need to do a quick folder merge! Which is all I needed for a project. I have BBEdit for file merges, but for just a quick merge, i like this (for terminal jockey's, well, why are you reading this in a non-text-based browser anyway?j/k).
I haven't tried 'synctwofolders, but this just works. A little explanation of which parent folder to select would have been useful, but it only took one error to figure this out. for free, hard to beat.