I've had my VFF sprints for almost 2 months. Great to find this site. I just started running in them on my treadmill (18" of snow). I've put about 14 miles in (about 5 miles each run) and some blistering on my forefoot. I guess this is just an adjustment period. Has anyone had any running experience with the KSO's vs. Sprint? I'll check the rest of the forum.