Great looking detail there Dave, you know your stuff.
Not tried Colli myself, tried most other stuff and now a huge Zaino fan. Must get a tub and give it a go though to compare.
You can use it on top of Zaino if you like, but then you wouldn't be able to use any more Zaino on top of the Collinite as it wouldn't bond - so once you use it, there's no going back unless you cleanse the car all over again (with for example Zaino AIO).
I rate the Collinite's durability though and it has superb water beading and sheeting - tight little beads compared to the larger ones from Zaino... nothing more than a cosmetic effect but its one I quite like :)