I was reading this thread on 2015 lizard batteries. Pretty interesting. Here are my conclusions:
2015 Lizard batteries - My Nissan Leaf Forum
The performance of the Lizard batteries is mixed. Some are doing much better than others.
The Lizard batteries seem to have some extra capacity over 24 kWh that is used to mask early degradation.
Now the less certain conclusions:
New cars with stock batteries are doing better than replacements in 2011-2013's.
Counterintuitively, cars that are driven more have better battery life.
Deep discharge is a killer.
I think we will continue in blissful ignorance, not taking any specific readings. But the range is still doing well so far.