Moodle is vastly superior to the commercial offerings as a research tool, since we can easily modify the code to support our research agenda and data collection needs.
I wanted to expand on this a bit. With commercial software your data is, in effect, held hostage to the continued survival of the commercial entity. Sometimes it's even contingent on continuing to pay the commercial entity. If you don't pay, your data goes away.
We've been burned by this a couple of times; in fact, I have a project assigned for my "free time"
this semester that involves trying to extract data from a commercial system that our university used to license, but doesn't any more. What I have is a (very large) collection of static HTML pages generated from the commercial software's database
shortly before the software was shut down for good.
I'll have to write some scripts to grovel through these, extract the data, and plug it back into another database in a form we can use. We're lucky that we even have the HTML pages; sometimes you wind up with nothing at all when the license for a commercial system runs out.
With Moodle, even if Martin and all the other developers disappeared tomorrow, our data would be safe, and would still be usable. Anyone who knows MySQL
(and spends a bit of time looking at the Moodle source code) can create custom data reports.
This may not be a serious issue for those who aren't doing education research, but it's vital for us.