First thanks you for your work, it's a good job ;)
It could be a good idea to used the commanderjs(http://visionmedia.github.io/commander.js/) lib to handle the synth bin.
Let me know if you are interested by this modification.
I could try to make a pull request if you like it.
Regards,
I briefly looked into using that a while back but couldn't figure out how to make it act the way I wanted the synth cli to act. If you can maintain the same functionality but make Synth's code smaller or more readable, then I'm all for it. Knock yourself out :)