As a lone developer this would make a lot of sense - however I'm working with others on these projects so it would be a pain to go this way.

I beg to differ. You and your collaborators could work together on a distributed git repo mirroring sourceforge on the master branch. You would do your collaborative work on various development branches. Someone would finally be responsible to merge the relevant branch to the master branch and then to push the changes to sourceforge. Again feel free to substitute mercurial instead of git.

However, a corollary of this is that it would be neat to be using a distributed system - is there any scope for doing that?

Our beloved overseer for life is not interested to switch away from subversion but it is very all too easy to create a mirror, as I did. Since I am the only person who has seemed motivated by git so far, I haven't made my git repo public but if you are interested I could push it to GitHub (I could also give you access to my computer but since I work from home, it would not be so reliable network-wise as I have got a rather hopeless ADSL at the moment). I may even be possible to put a post-commit hook on sourceforge to automatically push any new commit onto that would-be GitHub repo.

Best wishes,

Luc