It would be an interesting improvement combining the regenerative braking with speed (using a gain value), so the vehicle reaches a balanced speed depending on the TQ demand (brake potentiometer) and speed. It is something similar to what Curtis does with its "Natural Braking", but they do this when there is no brake demand, just when throttle is released.
The result function should be something like: "Braking Demand" = "Brake potentiometer" + "speed" (ERPM) * "Braking Speed Gain constant" (when "Brake potentiometer" > 0)
I feel that using the regenerative braking is a bit unstable in slopes, specially when the battery has a maximum charging value. In simply words: it brakes only a little at high speed (due to the max charge limit), but as the bike loses speed the braking increases, which makes the process to continue and braking more and more until the bike is almost stopped. It feels totally the opposite to what most vehicles do.
Having this improvement will not allow to brake more (as the battery has a limit) but it will reach a balance point and will not continue braking more and more (I have to be modulating the braking all the time, it feels little intuitive)