This should be at the top of the article to hush folks like myself who might be curious from the get go why another approach wasn't taken and why the Mac Pros were selected. Thanks for the insight as to the why.
And we actually run a lot of them in production, so I've figured out how to do it and not pull my hair out constantly. That's something I'd like to write on as well, but it would be in a different medium. More technical depth, less pretty pictures.
By the way, thanks for clearly, completely and patiently responding to people in this thread.
I want to explore the design decisions around the chassis in a follow-up, and we have one interview in the can already with the industrial designer. Hopefully that article will be a little faster to get out; this one was written about 3 months ago.
The other angle that I'd love to explore in a more in-depth article is how we actually do this stuff in production, and what we've learned about it. This would delve more into the ugly OS X stuff that we painted over to get things nice and pretty in production.