It turns out my run with the new shoes was a bit overzealous. I'm effectively couched for this whole weekend, nursing my ankles.
After the run I felt great, and thought the shoes were going to be perfect. I can't be sure if it's simply the distance or the shoes themselves, but whatever it was, I felt it later that day. After remaining seated for a few hours after the run working on things for class, I went to use the stairs in my apartment building on my way to campus. I felt a sharp pain in my right ankle when I put my bodyweight on it, and I retracted instantly. I tried again, same result. I promptly scheduled an appointment with an orthopedist to have my ankles checked out. I spent my evening seething at myself, fearing a stress fracture and the possibility that a doctor would tell me I couldn't participate in the events. You might imagine the anxiety I felt having been training for months only to have possibly put myself in a position of not being able to achieve my goal.
The next day the doctor informed me that he would "bet [his] house" that it wasn't a stress fracture, which was reasonably reassuring. He sent me home with some more ibuprofen and instructed me to stay off them, ice on 30 minutes, off 1 hour, and to try a run again on Monday with my old shoes. Until then I'm sedentary. Hopefully my training will pick up again soon, otherwise this blog will become decidely purposeless.