We've previously had Moodle and Mahara paired - the steps are well documented, and there are Moodle plugins to submit portfolios as assignments and visa versa (I've only tried these loosely, when helping test a 'new' version a couple of years ago).
We've had no need to get into the Competencies of the 3.x moodles to comment on. Lewis Carr was the local moodle wiz we'd ask to chime in on these things - he runs his own show now (not listed on moodle.org as an official partner) but has been working with the FA lately (and did a stint as a Moodlerooms Solutions Engineer) so has a big enough profile to be trustworthy advice if he spots this / has time to contribute.