They look really hot. Get a running pack from Patagonia.
Gimmick. A backpack should move with your movements.
Not nearly an expert, but welll seasoned runner/road racer: ran home from work through Berkeley and Oakland, circa 10 mi with some steep hills w standard light bpack w circa 6-8lbs for 9 mos. Mon-Fri. Sometimes had 12 lbs in. Result: no improvement in racing times, and a few years later developed lumbar disks 3,4,5 displacement. Doc thought it might have....likely...been the b.p.. Just me. But if I had a do-over? I wouldn't.
Try a messenger bag, and grasp the farthest corner.