Though I'd point out that I've started publishing an extensive, 6-part interview with author Paul M. Sammon (Future Noir: The Making of Blade Runner). The interview was conducted in 2007 for American Online, but it was never published. Until now.
I can't say for sure that there's heretofore unknown information revealed about the making of Blade Runner. Maybe minor things. You never know.
Here are the first 3 parts...