In our schools we encourage partners to communicate with each other what they feel, and if they can help, please do. People look at techniques very differently and sometimes someone can say something that will make all the sense in the world to someone not "getting it".
I do work hard to keep the ubiquitous windbags under control. And all conversations should be about the technique or principle at hand. You will often hear me say, "Less talk, more train." But being a little more open to verbal communication allows me as an instructor to see what is really frustrating my students. Knowing this helps me be a better instructor.
But, Opher, I really like the idea of a silent class. I may have to kick it around with my other instructors!