What I really want, I think, is some kind of meta-tool which lets me manage my build environment but by using the core tools - in my case Jekyll and Compass and probably a CoffeeScript processor eventually - so I (hopefully) have fewer maintenance problems down the line. Seems like Guard is pretty much what I want. I'm coupling it with guard-jekyll-plus and guard-compass to work with those tools. It isn't perfect, and doesn't assuage my dependency fears entirely but it feels a much more robust solution than the previous version.
My basic jekyll-foundation project has been changed to use this new tool chain and seems much more responsive than before (could be anecdotal) so I'm looking forward to making more use of it.