He's written several times about how BE has helped him. Here's his latest in a spontaneous email I received from him just this week.
I just got the music (3rd horn) for Verdi's Otello which we are performing in August. So far I've found horn in: Bb, C, D, Eb, E, A and A Basso, and your favorite, horn in B. He either loved or hated horns. Lot's of nice solos in the 3rd part. Dave threatened to take 3rd away from me and make me play 1st.
I don't think that anyone who has never experienced something like this could even remotely begin to understand. The old joke is that playing in a symphony orchestra is like flying: endless boredom punctuated by moments of stark terror. We've all been there and done that. But the thrill of getting it right is what keeps us coming back.... And actually, it wasn't until I started BE that I ever had any confidence that I ever would perform.
The Otello horn parts have stuff that is right out of BE exercises. I would never have thought I could play some of these passages before BE. Now it's - "Oh yeah, I know how to do that." I'm not bragging, it's just that I've done those exercises so much, that it's very natural to incorporate the BE techniques into real world playing. I approach every playing situation from a BE perspective, practice, rehearsal or performance, because first I have to be able to produce the notes. After that I can work on the musical aspects. If I can't play the notes, there isn't anywhere to go. BE has helped me make sure I can play the notes.