Well,
I got my Biv-1's and my Biv-3 last week and I have been methodically testing them on various sources.
Overall, I am extremely happy with these mics.
The Biv-1's had a really nice sound, great for sources with higher volume and where you want that Royer 121 sound. The mic was a coin toss on Viola agianst the Biv-3, different character, but both sounded fantastic.
But that Biv-3. Man. That's a beautiful sounding mic. It was amazing on Viola, acoustic guitar, and some female vocals I tried it on. I am not sure what to compare it to, but just based solely on the ear test, I liked the character of it. It just sounds like a much more expensive mic. Wonderfully warm and nearly perfectly smooth on top. No nasty hype.
FYI: Generally I was running into SCA n72 > Sta-level > Prism Orpheus. I haven't really tried any other variations yet. I am definitely going to be purchasing a cloud lifter, even the Biv-3 is pretty quiet.
Hopefully this is helpful to someone.