Never mind, I think I was comparing orange to apple. These two (uPortal and Drupal) are designed for very different purpose, and even some people had tried to customize Drupal to make it like a SIS (Drupal/CiviCRM), but I don't think it's fair to compare both.
Probably a better comparison would be openSIS and uPortal. Has anyone tried to compare these two (especially when integrated with Moodle)? Or, is there any stable php-based open-source Student Information Systems out there (e.g. RosarioSIS, which I haven't tried)? Thanks!
Wen