So buy the cheaper 82mm filters. It turns out that there is very little difference between expensive and cheap CPLs.
Maybe a bit better flare performance with the top end coatings on the B&W, but are you shooting into the sun with a CPL on? Anecdotally some folks claim the better multi-coatings are easier to clean, and so you can decide if that's worth ~2.5X the price.
I had read that article before and I'm glad you've reminded us of it. I had that nagging thought I was forgetting something important.
A straight line curve would be ideal, wouldn't it? It makes me question the high transmission filters, like the B+W, as they seem to suppress transmission of the violet and blue spectrum. I'd rather have the flattest line possible. Really piques my interest in the Zeiss T* CPL, as it seems to have the flattest line of those filters tested.