What he wanted most was a private office, and he got it, despite no one else in the company having one (it was kind of smallish and closet like, but he had a door that closed, and that made him happy). I always suspected that was a big part of why he was so productive compared to everyone else; though the huge amount of experience and his seeming disinterest in anything but churning out code (all of his hobbies also involved code to some degree, and he was always way out front on various trends in software development) were also big contributors. It's also worth nothing that he didn't put in long hours. When it was crunch time in the office, he wouldn't be one of the people there on the weekend. Paradoxically, I think that's another contributing factor to his high productivity.
So, yeah, I've often wondered whether Google/Microsoft/Facebook/etc. has internal metrics about this. Google is infamously an open plan office, Microsoft has offices, facebook is mixed (I think?). Surely, these companies who keep gigabytes of data about everybody on the planet has some idea about the relative productivity of offices vs. open plans.