I love 6v batteries because of their durability and greater amperage. When you hook two up in series you essentially have one HUGE
12v battery.
I used 6v batteries for years until last year when a battery post broke on one in my
Sovereign. I had no
12v power on the last day of a trip because of this and it really sucked. Failures are rare but they can happen. In this particular case, the fault was mine as the 2/0 inverter cable I had connected to the post was under too much tension. Would I use 6v batteries again? Probably, but it depends on the numbers and application. I may use them again for my Overlander.