Don't know if he used rigorous scientific methods, but several decades ago Jim Blackford showed that putting the load down low and distributed front/rear affected bike handling less than high and to the rear only. Don't guess that commuters will be much inclined to adopt loaded cycletouring techniques. The takeaway is probably that lower is almost always better than higher. For a while in the 80's - 90's I commuted with the load in front panniers on a lowrider rack.