the CDT, or any "frameless" pack, should be a limit of 25 lbs. there is one brand that claims it has a frameless pack that carries 30-35 without too much fuss. find it here: http://sixmoondesigns.com/packs.html?pa ... gory_id=11
(btw, i owned this pack, but the strap angle was weird on my smaller shoulders, otherwise a fantastic item)
six moon also makes other great gear, including the critically acclaimed Lunar Solo and Duo.
btw, "frameless" only refers to a lack of ptfe or other carbon/plastic/wood/moonrock frame, that is usually thought of as a sheet inside of the backpanel's foam.
this does not mean that all of these packs dont have a suspension system. many of them have optional or built in "stays" made of aluminum or carbon.
the Mariposa, Gorilla, Starlite, Swift, OHM, Circuit and others have a set or loop stay that will greatly improve handling over a plain fabric backpanel. The "stay" is designed to effectively transfer weight from the load lifters, to the hipbelt. In many of these packs, like my OHM, the stay(s) can be removed, when loads are under 20 lbs and the stay is not needed. (this is usually to the delight of us gram counters, as the stay can be as "heavy" as 2 ounces)