WOW I'll definately have to see that regulator, sounds interesting. That will level the playing field for sure.
Metering is not accurate compared to what? Can you reproduce the same readings of the same 18% gray card over n over in the same situations using alky bats? It only has to give you a reproduceable reading that you standardize to your film vs develping vs printing to make it do exactly the same thing every time. Meters are only as stupid as the user.
Whetstone bridges are a balancing act of current. They don't know light... just curent. It reads the photo cell as a variable resistor limiting curent on one side vs the other so the same amt of current will make the meter deflect the same amt every time. Linear? No, log.
Depleation of batteries is a few years down the line. I had batteries in my analog PentaxSpot meter for 5 years that kept saying the same florecent overheads in my shop are exactly the same exposure as the day I put em in. Change the battery regularly and you will never see the end of the curve where it breaks down. How long do your batteries last? Do they depleat every time you take a reading?
BTW if you have any old spotmeters (maybe any meters or cameras) that use mercury batteries you want to throw in the trash because they are not accurate enough with alkys, I'll take em all off your hands, I'll pay the postage. PM me?
Anyway... to each his own, how do your pictures look in the end is all that counts, not how accurate a meter you have. Many old timers never use meters, I hardly ever, except maybe as a referance starting point. I see it as a crutch like having a GPS take the place of my map n compass n the brain between my ears.