Thanks for the follow-up Sarah. I had some reservations about rolling with Jacob's post because I knew there would be an inevitable fallout of some sort. What really pushed us to move forward with it was the fact that pushing it out would mean helping a ton of people. To me, that meant the benefits outweighed any potential backlash.

No matter what Jason, or Joost, or anyone says about "fallacies", the truth is that the issues Jacob pointed out are real. Just like anything in SEO, the severity can be debated but in my experience duplicate content can really screw you, especially if you're a relatively new site. A huge site might be able to afford leaking out a bit of their authority here and there. On the other hand, someone just getting off the ground needs every advantage they can get. Hanging on to every ounce of domain equity can really help in that department and sometimes can be a make-or-break factor.

I'm really happy to hear that WP Engine is going to be working on implementing some changes to correct this stuff. The primary goal of this post was to help WP Engine's customers take care of this issue themselves in case WP Engine decided it wasn't enough of a problem to change their system. The secondary reason was to push WP Engine to make some real core-level changes to their server setup and it appears that we've managed to do that. Seems like a win-win situation to me. :)