On update on my situation:
After replacing both the solenoid and the controller, charging has returned to normal, but we also haven't had the high ambient temps when the issue manifested itself, so frankly I am not convinced it is solved.
However, now I've noticed both my Diehard Platinums are resting at about 12.2-12.3 when I check them after sitting overnight. The batteries are 2 years old at the most and the alternator is charging at the 14.1-3 range.
I haven't changed anything electrical wise on the JK so I am not aware of any parasitic drain, and since it is happening to both batteries equally, I'm wondering if I need to explore Ultimizer option, or if the NL system just can't handle the demands of the Platinum/Odyssey batteries. Connections have all been double checked.
I'm wondering who else is running the NL system and Diehard Platinum/Odyssey batteries and having issues? I met with Kelly M and he is having the same issues I was originally having, even just after a 30-40 minute drive in our current ambient temps here in SoCal. He has different batteries (he'd have to chime in on the brand) but otherwise are setups are identical.
Possibly I have a couple bum Platinums, and it has nothing to do with the NL system, but I am questioning both at this point.