Well, since Nathaniel isn't going to advocate Monotone, barking up his own tree, perhaps I'll do it! Monotone is solid, especially for a system that is evolving so quickly. There are a lot of great work being done there. It has one of the most thorough test suites I've ever seen for regression testing; bugs that get fixed don't get a chance to resurface. The upcoming release of 0.26 will bring in some important changes to the software, making it more robust, quicker, and more useful. Honestly, I cannot see working with any other tool, now that I've worked with Monotone. Here's the recent pre-release notes for 0.26pre3: http://www.venge.net/monotone/NEWS.pre.