You're not understanding the difference between speed vs power based PAS. Of course, all assist systems have to apply power to move the bike, and that amount of power can vary depending on the programming. That doesn't mean it's not speed based. The key to the difference is whether power is dropped when you hit a specific speed. The newer Ride1Up bikes and newer Radbikes do NOT drop the power way down when they hit a specific speed because they are not programmed to do so in current generation bikes, only the older (or much older) models. So with current models, it's easier to pedal faster than the baseline speed with no need to increase the assist level. For the Espin, it looks like they still have a speed limit in place with each assist level where the power is dropped significantly once you reach it, like hitting a wall, so you really need to bump of the assist level to go faster, which you said so yourself. That's too bad, but it is what it is.