Now I'm a cheapskate, but when I looked at the options on the Four, it seemed like the $8k didn't buy much; just fluff. If you got the Prime, at least you'd be getting something of substance for your money. I couldn't find a One; that's what I'd have gone for. So I "settled" for a Two. I'm not sure I believe that the 2016 is the same as the 2018 or 2019. On paper, maybe so. But there are ALWAYS bugs in the first year of a new model that they couldn't find just with internal research. If they're not big, they just fix them quietly for the next model year.