Your generated current would be a function of your motor configuration, speed, bike weight, and incline. The most I have seen is 30A braking while going downhill from 50mph on a 150lbs bike on a QS205 motor (V3 extra copper fill and 50mm magnets). That's at the max regen force setting of 200.
For the most bikes (like those with MXSUS 3K and aluminum frame, i.e. with weight in the 80-90lbs range) the setting of 100 would be just right. But you can set it all up to 200 and then work it down to see which one is best for you. No harm doing that.
What's a good value to set for regen force?
I use 10 of these batteries which have a max charge rate of 5C. So my 20S 10Ah pack would have a max charge rate of 50A.