Well, in the end I've decided to return the AT2022. I tried to test the bias voltage issue (discussed in
this newer thread), but I just don't have the right gear to test it, or the time to build it. In general, I think this mic is a decent budget mic and may do a good job for some but it does require some massaging in post (a bump in the lows and some cutting in the highs). The highs in particular I found to be overly pronounced while the stereo imaging seems a little unfocused.
I think my "ears" (not my hearing...) and my sound system have improved over the last decade and much of what sounded good to me 10 years ago, sounds quite different to me today.
After hearing some impressive recordings online, I've decided to go for the BP4025. I considered the NT4 again, but in the end, I really don't find its size and weight convenient; I've also read many complaints of it's high sensitivity to wind while the 4025 gets good marks there. I realize the AT8022 is probably a good intermediate, offering both battery and phantom power, but I didn't find any recordings done with it and one person complained extensively about its inadequate stereo field. This could be due to the fact that the AT8022 capsules are both perpendicular to the front center, while the BP4025 capsules are at an angle towards it. For the difference in price, I figure I'll go with what I'd heard and liked. Some of the nature recordings I listened to were quite spectacular both in imaging and frequency content. And the near-absent noise floor is a real plus.
What finally sold me was a piano recording directly comparing a VP88 to the BP4025 I found on GS: there was a clear difference between the two recordings, mostly in favor of the VP88. So I downloaded both tracks, stuck them in my DAW and with some stereo image widening using MSED and a little EQ (oddly close to the AT2022 EQ I was using before, but less extreme...), the BP4025 recording ended up almost indistinguishable from the VP-88 one. In that recording the BP4025 was a little over-bright, which will be a good thing if it's buried in foam and rat-fur in the field.
I decided to continue this thread because it's more about stereo mics in general. I'll post again when I get to try out the BP4025.