Hiro11, I originally was fitted by the tri-store (they did this test thing) and used those shoes for a year. I got 300-400 miles on them before they gave up the ghost.
Then I went back and bought three more identical pairs for this crazy marathon endeavor. I have been rotating those three pairs. As I get closer, I am going to pick the two best for the actual marathon (one for my feet and one for the emergency drop bag in case it is raining or something).
I am a noob and probably making some big mistakes, to be honest. But at least I solved the blister thing so my girlfriend is breathing a bit easier now. I just want it all to be over.