hgsubversion - since you occasionally encounter SVN and often get annoyed that you can't switch the working directory between releases, you can simply use hgsubversion. This mirrors a complete SVN repository into a local Mercurial repository from which you can easily populate your working area using Mercurial tools. Also useful if you want to manage patches for an SVN project, as Mercurial's patch queue is superior to all SVN-based techniques.