I had a lady friend looking for something fairly non-edgy for live and didn't like the proximity tone change. That's when I learned these were in that style, and based on my experience with the RE-20 on acoustic guit (live), went ahead and got a PR-20.
I've only tried it on a few tests and (my own) live vocal (electric/semi-acoustic sets) it did as expected, stayed fairly constant, no big curves. Mixed with the other vocal mics on the bandstand, I had to do my own bump (6k or so) to fit in.
Anyhoo.. this a fairly cool niche these do, at nice price.