This is just an FYI, based on my own experience, for those looking further into this cadence only vs. torque sensing. It's very likely going to add to any confusion regarding cadence based potential. There ARE some cadence only controllers that allow the rider to choose between "speed" based output, and "power" based output. A LOT of experience here with the after market KT controllers, and UART based Bafang mid drives, both with this ability. There may be others I'm not familiar with. I do a lot of riding using both cadence and torque sensing, and this power based cadence makes the call about which is the better of the 2 MUCH more difficult....
MOST of the geared hub e-bikes sold come with speed based cadence only systems - and they generate a LOT of complaints related to poor low speed control of the bike. The bike "takes off on me as soon as I start pedaling" and "the bike is too fast" are REALLY common. This is because the bike is equipped with a "speed" based system. The PAS levels are set based on speed, and are kinda like on off switches. An example might run like this. From a stop is PAS 1, the bike will accelerate to 12-13mph while being pedaled. Stop pedaling, the motor turns off, and you coast. Otherwise, if you continue pedaling, the bike continues to accelerate to a predetermined speed established by the PAS level selected (PAS 1 = 12-13mph often). This makes it impossible to pedal continuously, maintain cadence, at low speeds (6-10 mph for instance).
THEN, there are the controllers set to use a fixed power level, based on selected PAS level, regardless of the bikes speed. These bikes have a TOTALLY different character, and show perfectly what CAN be done with a cadence only based system. Set to PAS 1 for instance, a fixed amount of power is supplied to the motor while the crank is being turned. The amount of power is often set to allow the rider to MAINTAIN cadence while running just 6-7 mph. A higher speed (or more power, for a hill for instance) is available by simple setting a higher PAS level. This chosen amount of power, selected using the different PAS levels, DOES NOT change with changes in speed like the simpler speed based systems above.
Bottom line, the "power" based cadence system can be thought of as having an adjustable (per PAS level) assist level, as in practice, that's exactly how it's used. My hope is that as the e-bike industry matures, more will learn about this power based system and start demanding/forcing the bike manf's start providing it, moving the speed based systems to the dark ages - where they belong. -Al