Brief update. I'm fairly certain I got a bad battery from Braille/HP.
Despite being 12 V nominal the M3 battery is supposed to be in the range of 12.5-12.8 VDC (or something close to that, don't recall the exact spec). My OEM battery is 12.7-12.8. My Braille is running 12.3. The problems that have ramped up steadily since my install are varied and troublesome. They include:
1. A lift icon on startup. Apparently some generic warning that you need service. An exclamation point in the center screen speedo/odo area that one you cycle through the stalk display options it tell you low battery. Now to really offer maximum redundancy I also get the terrible English warning of "increased battery discharge". "Low battery" or "low battery voltage" would have been a much better English translation
2. Comfort acccess one touch entry usually fails.
3. Car does not remember time/date and trip odometer reading after shut off completely. Not having a clock in your dash/iDrive = major annoyance
4. Safety lighting feature works intermittently. (The one where you can blast your high beams for 10 seconds or so after you kill the engine to light up an area in front on you).
The helpful folks at Braille confirmed that their battery FULLY meets BMW specs of 12.5-12.8 and should ideally be right around 12.8 just like the OEM battery. They took my credit card as a deposit to return the current battery once the new one arrives, which is convenient. Unfortunately I actually caught them out of stock which seemed a bit odd.
It is quite surprising how sensitve this car is to a 0.5 V change and being just a few tenths below below spec. Seems a bit like bad design - it certainly is not robust design. I realize you need a specification and the spec is typically driven by certain component requirements. Nonetheless, it simply doesn't seem impossible nor difficult to make the car work fine with anything from say 12.5+/-0.5.
I greatly look forward to a bug free electrical system very soon.