I agree with Dwayne. If you can afford the entry fee, the custom made McHale Packs are of outstanding design, impeccable craftmanship, strong as all get-out, and live up to the hype.
Though I have a custom made 5000 cu inch plus panel loading pack, made of 420 HT Pack Cloth and Full Spectra Fabric, it is not what would be considered an ultra light pack at about 5.5 lbs. But as a photographer, carrying my cameras up to 4″ x 5″ (camera alone is 7.5 lbs), lenses, tripod, film, filters, meter, and all the rest of the backpacking gear, as well as food, and water it is without question the most comfortable pack that I have ever used.
Though I have not had the opportunity to use my pack much it will easily be able to carry 50 or more pounds comfortably and the straps and waist belt should not slip as I have experienced with my other packs in the past.
The aluminum stays of the McHale packs can be removed. Many of the lighter packs are designed to function with and without stays and to adjust the size and length of both the stays and packs.
As Dan McHale points out regarding the price of his packs you will not have to go through the number of packs to finally find one that is fit to your size, is comfortable, and may well last 10 to 20 years. In addition, Dan is of the opinion that Pack weight is not where one should lessen the weight to below about 2 – 3 pounds. This is because a full pack will carry better and more comfortably with a frame, better shoulder straps and waist belt. A 1 pound full pack without a frame weighing 22 pounds will not carry as well or as comfortably as 3 pound full pack with a frame weighing 24 pounds.