Whether you have a torque sensor or speed sensor makes little difference. What's important is the software in the controller that should process the torque or speed signal into a meaningful power profile. Only the European and Panasonic power systems have managed that so far with torque sensors.
With every type of system, there's advantages and disadvantages. With the Chinese speed sensor systems, the power tends to remain steady, so that when you start pedalling, you get the power set on your control panel, which gives a relaxing ride with the motor keeping the power going, so you don't have to pedal hard. In fact you can pedal as hard or softly as you want, which is a huge advantage. With some torque systems, the power is proportional to pedal effort, so you can't ease off on your pedalling when your tired.
The situation is really confused now that the Chinese are fitting torque sensors to bikes with speed-control controllers, and now there's speed-control controllers with torque sensor simulation.
They all work. My preference is for a hub motor with speed sensor and speed-control controller with several levels of PAS.. Torque control is better for crank-drive systems, but only with current-control controllers, which is what I believe Bosch, Panasonic and Kalkhoff use.
