This question is about an ebike but I think the topic is more suited to be answered in this forum because you folks are more likely to be packing weight on your bikes.

How important is the weight distribution between the front and rear of the bike? I am doing research on the best way to convert a bike - front, mid or rear motor - and am concerned about the handling characteristics of the bike with an additional (at least) 20 pounds of weight, ultimately 50 pounds, plus frequently a person on the back.