This is a terrific discussion and I've enjoyed watching it. 

I wonder though if the issue of numbers of people in a classroom is the
whole point? Do you think that the average teacher who is accustomed to
teaching a small class is equipped with the necessary skills to teach a
large class? The presentations (eg lecture or textbook readings) and
demonstrations (eg short play or video) might carry across, but the
interactivity strategies must change radically. These alternative strategies
for interactivity in large classes certainly do not need to be experimental.
Tried and true student-centered activities can be implemented successfully
with a strong accountability system in place. The question is - who does
this well and with what levels of admin support?  I imagine this kind of
person who can do this has acquired several expert-level skills in pedagogy
as well as in management -- and really, let's face it -- considers his/her
work in the classroom as an art. 

Randolph Hollingsworth
Kentucky Virtual University
Council on Postsecondary Education