Well custom changes to most packs can drop the weight significantly.
Simply removing the hip belt and sternum strap from the Kumo will make the weights virtually identical. Better yet, you can drop to the super-lite robic like fabric of the Murmur if weight becomes a problem, keeping the sitlite pad. I have had the new Murmur to 25 pounds while testing it.
Note that I was not using the extension collar and was carrying the SVEA, saw, fishing gear, and a three layer NightLite pad for a week(8 nights) of fishing for brook trout along the NPT. (Hey, I even had an 8ounce bottle of Everclear 190 for a relaxed trip of fishing, eating, and having a couple drinks around a camp fire.) All in a 11oz pack (not counting the pad.)
For a more rugged pack I would choose the Kumo, though. Out of the box, it is a sturdy pack. Adding the pad increases the load carrying to about 30 pounds and it takes the occasional off-trail foray fine. I would hesitate before going to a stripped down pack and loosing the external pad keepers, hip belt, torso strap, etc. Though for a weekend, I might do it if I was peak-bagging.
The CDT looks like it would carry more weight, but, it is a small pack. Placing another 4-500ci inside (foam pad for support) would make it smaller. But, it has a larger volume than the Kumo/Murmur to begin with (~3000ci vs 2200ci for Kumo/Murmur.) I personally don't care too much for "tube" style carries, rather prefer the flatter "pad/frame" type carries of the Kumo/Murmur. I never use the Sitlite pads as a frame unless I tape a few together. Much easier on my back. I suppose you could fit these internally towards my back…but, as was said, sweat will be a problem.
It carried easily.
