Before updating the firmware I had a big problem with the SB910 flash not firing, and ended up with several shots significantly underexposed shots (inset original). There's sufficient latitude in the raw files, however, to recover the image without introducing much noise and maintaining a lot of detail. Of course, it's not nearly as sharp as it would otherwise have been. But hey, you can't have everything.
(1/200 sec, f2.8, ISO 200, AWB, spot metering, 24-70mm lens at 70mm)