I did the exact same mic mod (following in Fragtality's footsteps) and it works great! No Mixamp for me though, unfortunately.
Just out of curiosity, Did the photos of the headphones get mirrored somehow? Unless I'm mistaken, the cord comes out of the left can, so that first pic makes it look like it might be backwards (or maybe you just swiveled the mic really quick for the sake of the photo)? I am probably completely wrong and now have to go home and check how I have it setup