FWIW:
6906 w/standard 12 round magazine..
6906 w/standard (5906) 15 round magazine: (using S&W grip extender)
I actually prefer the "feel" of the 6906 w/the 15rd 5906 mag over the standard 12rd mag w/fingertip ext.
Hey, three free rounds, can't beat that..
Best Wishes,
Jesse