Hi Marc,
Have you tried Sakai? How does it compare to Moodle in your opinion?
In this field I'm far too novice yet to have an educated opinion. :-)
I suspect, though, that in the case of comparative systems I'm somewhat
challenged. The institution at which I'm doing much of my "web community
architecture" work has a heavy existing investment in Moodle and is
unlikely to change quickly, even should superior alternatives appear
(http://moodle.yorku.ca/).
Having said that, it's always a good idea to be aware of the whole
landscape, to have at least one person on the team aware of the
alternatives. And the nice thing about open source is that "borrowing"
worthwhile features from other packages isn't just allowed, it's
standard practise. :-)