update: I tested the PE and it's MIDI IN is working and passing note data through to the PE MIDI OUT.
Any other ideas?
For some reason the PE's not recognizing the file as valid sysex. Either there's an issue with the update files (the archives aren't corrupt, but Yahoo has been giving me problems with files over chrome in the last day or so) or it's an issue with the USB-MIDI interface.
I'll look into the interface and drivers later today.