Have not ever done this brine the brisket process before Tony and I purposely went pretty light on the salt/pepper because of my uncertainty. I take it your rub doesn't have much salt or is there some salt voodoo that would change salting and resting vs salting and cooking if used in equal amounts?
The injection seemed pretty hot w 2 tbsp of Crystal hot sauce so maybe it will overpower their taste buds 
Looking forward to reporting the good as well as the...what happened 
No salt voodoo, just chemistry! The brine infuses a certain amount of salt into the meat (but not as much as you would think). The main purpose is that the salt modifies the protein molecules, near the surface of the meat, which causes them to expand and "seal" the surface, thus retaining moisture (it can't escape as easily). Now, even though you rinse the meat, there is still residual salt on the surface. It's not that you put more salt on the surface, it's the length of time it
stays on the surface.
We can achieve the same chemical reaction by coating meat in salt, wrapping, and resting in the fridge overnight. But, this process isn't as efficient as a brine, and certainly not as flavorful! So, by brining, and then adding more salt overnight, you run the risk that the salt will liquify and essentially "brine" the meat a second time. By adding it right before smoking, it kind of infuses with the bark, and stays on the surface. At least, that's my theory....I could be wrong!
That's why I'm looking forward to your results, to see if I'm right or wrong.
If you went light, I'm sure you'll be fine! Beef can handle salt.
As for the injection, you really don't taste much heat, but more the flavor profile of the Crystal hot sauce; it gets pretty-well diluted in the meat.
