I'm very glad to have the 30 kWh pack. It's a late-2016 with 29k miles that's shown 12 bars in the 13 months it's been with me. I don't know if it's had a BMS update. It's very helpful to have over 120 miles of range in ECO-mode in nice weather, and the extra capacity lets you be easier on the battery (not charge it all the way), and have enough safety margin left over. When charged to 100%, it gives me the confidence to take mountain trips and go camping (with public charging). I took it over an 11,300-ft mountain pass in August (and plan to again this year).
I didn't find Carvana to be very competitively priced on LEAFs when I was looking (although they seemed competitive on the Fiat 500e and Spark EV). I too didn't feel entirely comfortable having them bring a car to me, where I would feel more obligated to commit. This LEAF had been sitting on a GM dealer's lot for a while. It didn't make a great impression in the ad, and wasn't on my short list, but completely sold me when I went in person, and I brought it home the same day.
2016 LEAF S-30 w/QC "Lexie"