New Caleffi polymer manifold

I'm hoping @hot_rod will weigh in, but any comment is welcome. I'm working on my distribution system, and bought a brass Caleffi 8 zone manifold. (inverted style) I'm going to buy additional ones for the rest of the project, and just saw the newer Model 671polymer ones. I have a few questions about them.

1. Are the adjustable flow devices interchangeable with the brass manifolds?
2. Will a Uponor 1/2 or 3/4 adaptor fit on the supply or return? The style that directly connect Pex type A expansion fittings? I see they have a quick release fitting adaptor of some sort.
3. Are they less expensive than the brass units?
4. Are they currently available? I searched for over an hour today, and did not find them for sale anywhere.

My thought is to buy one of the polymer units for some circuits that will only have Pex tubing connected to them, and no steel radiators, etc.

Thanks for any help that comes my way!