Loved the article. Something I have always believed in and have been in innumerable number of arguments on the causes and effects of having multiple people working on the same project.

I believe efficiency goes for a toss not because of the number of people interrupting your line of thought but because of the number of egos clashing.

I can relate with your take on the collective code ownership and physical space. Devs should feel comfortable in any part of the code base. But a code base also needs leaders. And when you force developers into a crammed team room in the name of collaboration, you often see the ipod headphones come on and people tune out.