Comparisons and advocacy

I know, the enquiry is ancient. Still some key thoughts common to this kind of questions for the next visitor:

TASS is closed source, right? They talk of "Whether that be in the 'Cloud' or on-premises" but I haven't found the license nor installation instructions. 

I that case the Moodle developers have no motivation to implement a "connector" to TASS, unless somebody comes with a contract. To make the matters complicated its API is not even public. Moodle has a set of APIs. So the only chance is for TASS people to implement a connector to Moodle.

Perhaps the whole thing is a misunderstanding. You say "testing Moodle as an alternative", but they are two things, Moodle is a LMS not a SiS. You seem to be looking for a SiS.