But I still don't feel like I understand if 2017 can be considered a real improvement on 2016. Did the BMS make the 30kWh merely as good as the 24? Or truly fix it? Or it's even worse than nothing?
Good questions that we'd all like answered. Before the 40kwh replacement packs started showing up, my advice was to look for a 30kwh pack with excellent LeafSpy stats and 12 bars BEFORE the BMS update. My best guess is that there are bad 30kwh packs, mediocre 30kwh packs, good 30kwh packs, and great 30kwh packs, but the BMS update makes it hard to determine what a particular Leaf has got.
Now my advice is to look for either a great pack that doesn't need the "update," or a terrible pack that is already down 2 or 3 (or 4) capacity bars AFTER the update and is almost due for a 40kwh warranty replacement.