I don't know how many have lost significent weight, but I can terll you from experience it really does make a difference. I recently lost more than my (heavy) base pack weight. I commented to my wife that on my annual trip it should be like walking out (it's all down a step switchback trail going in, up coming out) without a pack. ;) I figured that wouldn't really be true as I was now not as use to carry the extra weight, etc.
Well, it was. I was surprised. I lightened up my "carry weight" by 40 lbs without spending a dollar! :)
