I agree that webassist offers more potential for customisation but also that it does require a deeper understanding of the code behind these kind of products.
I would choose WA stuff over ADDT stuff now even if ADT was still alive due to the much smaller footprint and resulting quicker load times.
The only major drawback for me, and if this was addressed WA stuff would be perfect(!), is that you can't customse where all the includes are saved to. You have to have them in the various WA folders at the root of the site, which is messy for me.