Docpad is really, really a great static generator. It doesn't use a lot of files, its file architecture is easy to understand, and it's node, so I don't have to hack with ruby versions.
My advice to other people considering making a static site generator - please don't make another compiler or caching layer just like the rest, anyone can do that. But if you want to make a large difference, one that you can't do alone, then see if you can team up with an existing project, they'd certainly welcome your insights and probably have a ton of ideas already - the conversations will always be valuable for all parties involved, and the end result for the world will be much better quality solutions rather than just merely more solutions.
Cheers, Ben.