I watched that some time ago. Ha, I remember him missing all of the targets when at a distance. The 5" would improve his success. At present only Crete can hit anything at that distance. As far as the "improved" goes.....well uh...I guess so. The pistol has the captive recoil spring assembly which people have asked for since day one and the decocker which has been dropped. Other than those two items it is the Q pistol than came out in about 2011.
Seems Walther has played around with the chamber and feed ramp chamfering along the way also.