I have been looking into this method here recently. I have an injured right knee due to a tear in both my ACL and Meniscus. I have done some research on the topic and with my medical knowledge (which I am only a Med STUDENT, right now) it seems to be a pretty legitimate method to train harder with more than 50% of the weight taken off. If anyone has long-term experience with this, I'd love to PM about it or here about it here.