Another thinking-out-loud topic here... I'm re-evaluating weblogs.ucalgary.ca - what's worked, what hasn't, what could be done differently. It's best to take a long, hard look at it before it really takes off. There are a bunch of users in it now, but a critical evaluation of it is pretty important before we get into the hundreds of users level... I'm also colouring evaluation in light of the PLE/EduGlu concepts being rolled around. Perhaps the need to have a communal blog hosting service on campus is less important, or unnecessary, if that function is pushed into an aggregator service where it should be, rather than in the hosting side of things.
Elgg has improved a heck of a lot in the year since I quietly rolled out weblogs.ucalgary.ca (powered by Drupal at the moment). I really like the simplicity of the Elgg interface - helped by the fact that it's not trying to be a Swiss Army Knife, as Drupal is.
In the back of my mind, I had been hoping to keep WordPress MultiUser as the backup plan in case Drupal didn't work out. Elgg might be a more appropriate alternative.
Also, it's not that Drupal isn't working out, it's just that weblogs.ucalgary.ca doesn't have the right feel - it's not a personal environment, it's a commune. That makes it harder for an individual to find their own voice in the mishmash of common spaces within it. Elgg and WPMU are better as individual spaces, with varying degrees of built-in aggregativeness (Elgg has some cool Friends features, WPMU would rely on external aggregation).
So, in assessing plans B and C, has anyone successfully migrated from Drupal to Elgg or WPMU?