I look forward to discussing this further with you, and then sharing any pertinent results on this (or other) thread(s).
I agree, so lets keep the discussion here.
For those looking for the best(most realistic) PAS experience w/out breaking the bank, should try out one of the newer sine-wave controllers w/ one of their SLCD displays.
Your typical 3-level square-wave controller uses speed (motor RPM) values to limit the set-levels. For example, a mini-motor might have limits of 12 mph, 16 mph and 20 mph, in either cruise or PAS. This works well enough on a low-powered system, but as system power increases, the crudeness of this approach comes to the fore. Imagine a system with a 2 nd. level speed of 20 mph. When the rider stops pedaling, slows down and then re-engages, the motor wants to rush up to that speed level, making for a "jerky" response. Also, as system road speed increases, having only 3 levels can leave "gaps", not leaving the rider the option of setting a speed exactly where he/she wants it to be.
The sine-waves, on the other hand, use Current (Amps) to trigger the PAS levels, making for a more intuitive interface between the rider's input and the motor reaction. It imitates the strain-gauge approach of the higher priced system like the Bionx, hence the name "Torque Imitation" those Chinese engineers have gifted to these systems. And the 5 levels better cover the road speed range.
The first of the sine-waves were offered by BMS Battery several years ago and I tried both the SO6S and the S12S, both w/ the SLCD-5 display. The lilliputian 15 Amp (on a good day) SO6S was under-powered for my Q100 mini motor and the huge S12S was over-kill, but my biggest problem came about because of the odd Voltage of my LiPoly packs. These systems use "Auto-ranging" to read the initial pack value at start-up and that value determines some of the associated parameters. Others have made the LiPoly/sine-wave combo work, but I felt it never was glitch-free.
Recently, the new "KT" sine-waves have been available, mostly from PSW Power (Elifebike), so I thought I would give the "middle of the road" 20 Amp KT controller and LCD-5 display a try;
http://www.pswpower.com/peng/iview.asp? ... 33C0.50CGS
http://www.pswpower.com/peng/pic.asp?Mo ... ID=S220052
But once again, I had some issues w/ the LiPoly and auto-ranging working together and have come to the conclusion that these sine-waves work best w/ the standard 36 V and 48 V Li-Ion batteries.
So after one test ride, I went back to my "tried and true" ELB 9-FET square wave.
Since you need a controller, if you wanted to try this system out, that would be fine(pay me if it works out).
But as I mentioned before, often splicing into a "commercial" ebike can be tricky. If I could see your bike, I probably would have a good idea if it could be done and what it would take to do it.