I would want the Polarizer mixer included, that would make it an amazing module, I see it as essential really, and I say that based on using the A.Sol. envelope with them.
As far a separate module, well, it would probably take a bit more space as it would have inputs, and cost twice as much than if it were included. I'm still all for the dedicated polarizer mixer, but I'm glad to see Doepfer starting to add mixers to modules, the lack of them has been the main "complaint" of many people I've talked to about them. Without a mixer you're missing lots of potential from a module, I know you can always use one, but often that's an after thought and I'm more likely to tweak it if it's there, than to re-patch things to a mixer. Just my opinion.
So...here's hoping the P-mixer is included!
best,
phil