I've had my Kifaru DT2 for awhile now and seem to get lower back fatigue from the lower lumbar pad. I've tried multiple heights with the suspension but so far nothing seems to help. Put close to 40 miles in it with loads from 35-65 lbs and my only complaint is the lumbar pad. I've not gotten a blister or rub marks but my low back feels like its getting the skin rubbed off. I have even tried different shirts while using it. Also after about 2-3 hours of hiking my lower back muscles are tired feeling and sore, no bruising either. I'll call Kifaru this week when they open, just got back from the woods so I thought I would throw the question out here as well.