Thanks all for sharing your input and photos! Some convincing arguments for going the 35 route, and it'll be great to have one less thing to think about while shooting. Now it's just a matter of keeping an eye out for a discounted used biogon.
I appreciate the the alternative recommendations of the color skopar as well. I didn't realize what a great performer it was! It also led me to reading up on the nokton 35 1.4 as well and thinking about whether I'd miss the speed. With so many great choices, perhaps renting and trying is the way to go...
In any case, I'll post here what I eventually end up with.