The fact that you were able to run the battery down so low that the boost converter started to dropout means that the Power Distribution is doing EXACTLY what was intended - ie successfully power the cRIO and wireless adapter until the battery starts sagging < 6V. I'd consider your observations to indicate an excellent test of the PD ... and it easily passed.
Thanks for the feedback! I'll bet you'll be more careful about keeping your batteries topped off from now on
Russ