Again, The question was should OP upgrade to a 17.4ah if they want to travel at assist
level 3, with a 20mi commute, on hilly terrain with a single charge? The OP is not on flat land texas or throttle in the mountains of Colorado. Neither is the OP trying to travel 30+ mi at 30mph. Because you seem to be in a situation that is perfect conditions for an ebike (and not your exaggerated examples) doesn't make it universally applicable. Taking into factors that the battery should be charged ~85% and the motor starts to sputter under 30%, during real world performance, I suggest OP buy a 17.4ah battery for that situation. My situation also warrants a 17.4ah (21ah can't fit in s/t). I am considering a 17.4 battery and an 8.8ah backup. I'd carry the 8.8ah instead of a charger on longer rides and can be swapped out for the home stretch or errands with less bulk. Lots of local rides are atleast 20mi round trip through terrain, which I wouldn't feel confident doing on a 12.8ah battery. What made you go for the CC-S over the CC Air or light bicycle if you are always in eco boost?
Niche isn't bad, toys aren't just for kids, like supercars or 3d printers. CC-S is still probably the best sub $3k ebike but there are grey areas in the market as well. Are e-bikes bulky overpowered bicycles, slimmed down under-powered motorcycles, gas alternative, all terrain or road, etc? My state won't all ow me be register as a bicycle because it has motor assistance, and can't be a moped because it has pedal assist. Battery/mileage is always a limiting factor whether phones or teslas. I would compare Cross Current to the iPhone, the Cross Current S to the iPhone 3g, and hopefully the Cross Current 2020 will be the iPhone 4s. Advancements from CC -> CC-s, seeing prices for battery packs increase in size and decrease in price, and even kickstarter (see: delfast bikes), are encouraging but I don't think you could convince a college student to buy an CC-S over a beater car or moped.