I just got a Zpacsk Ark Haul. 24 oz and capable of carrying 40 lbs. Have tested it at about 27 lbs and I forgot I had a pack on. I see no problem with taking this to 35 lbs. and beyond. the weight transfer to the hip belt is awesome and the hipbelt has upper and lower adjustment straps so the pack stays in place without having to be overly tightened.

Of course YMMV but they do offer a 30 return. They certainly aren't cheap but you get what you pay for...
Just an old newbe