I have the V3 display and connected it with the Bafang Go+ app. You can adjust acceleration feature and startup angle (valid for all 5 PAS) the speed limit for each PAS, and the max. output power for each PAS in a very limited range. I played a little with it, acceleration feature i could not...
You have to check it with the frame, or maybe someone here is willing to do with a 216 shock at hand. Then You have to be careful with shock stroke - 60 mm max I would guess, compressed length 156mm. @TCFlowClyde is running 210x55, compressed length 155 mm with no problems. (Yet 😂).
Edit...
That’s always possible. But the BB hight will be lowered significantly, appr. 20mm. And the BB of the frame is allready low. You could only compensate with longer shock (216mm) and longer travel fork with increased Axle to Crown length.
Be careful. 200 x 55 does not work. 210 x 55 may work, see @TCFlowClyde posts. There are some reports here that coil shocks doesn’t fit due to interference with the seattube.
The sprague bearing / one way clutch in the motor that engages when You start to pedal. Same functionality as the freewheel on Your cassette hub.
Edit: Looks like i misspelled it. Its sprag clutch. Sprag clutch - Wikipedia
Can You judge if the chatter is caused by something rattling inside the motor, or if it is caused by chain backslash rattling on the sprague bearing - same as M510?