On battery degradation, this may or may not be a fair comparison (the very short answer - I don't think you will see any).
My 2014 FFE has roughly 24,000 miles on it in three years of use. I'm not sure I can see any battery degradation at all. I guess if I spent a lot of time working at it, I could possibly see some. Comparing ancient charging records.
We just bought a 2013 FFE with 36,000 miles on it. Been driving it now for three days, the same commute as the 2014. There is virtually no difference in the range on the newer, higher mileage car. Honestly, can't tell the difference at all (other than the older car drives better, sounds better, and doesn't have any rattles).
Yes the scientific experiment would be to actually test both cars and see if either has battery degradation (however the group has figured out how to measure the battery capacity). But from where I sit, there's so little difference, it doesn't really matter.
Now the 2014 spent three winters in Chicago. The 2013 spent three years in California. Could that make a difference? I'd expect it would, but the two car batteries act exactly the same side by side in the same conditions.
By the way while I was doing some work on both cars, I discovered a small amount of surface rust on the seams of the frame of the 2014, Chicago car. The California car, not a hint of rust anywhere. Now I see why people want real live certified California cars. You guys don't hurt cars at all. And you don't have any potholes, so the cars hold together better. I bought a year older car with more miles and it runs better - go figure.