In my personal opinion de answer is yes. With 20lbs and with much less weight.
In the last 5 years i Worked very hard to carry as less weight as i can.
Nowadays i carry a sub 5 base weigth (most times 4 lbs) but when you add food and water (2.5 liters and about 1 to 1.5 lbs/day) my final starting loads are about 13 to 15 lbs (for 3 to 4 days walks)
I been using several UL packs as GG whisper (with belt) and mariposa golite jam, jam2 and ion, grivel air tech 28 ….. and several alpine packs (heavier)
Some times the difference between a full suspension pack and a frameless pack is less than 200/300 grams (7 to 10 oz)
This small difference is really big in confort terms, is much more confortable carry the weight in your hips using the hipbelt.
In my lghtest pack (the fantastic and now discontinued GG Wishper) the hipbelt means 1.5 oz more and using a rolled pad as a frame its possible to carry most of the pack weight in your hips.
I modified mine jam and jam2 with a light plastic sheet inside the pad pocket, to create a semi rigid frame and transfer the load to my hips, with only 60 grams more i felt that now i carry heavier loads in a more confortable and effective way.
Of course if Im writing about Sub 5 packs as much more weight you add more important the frame is
I read frecuently that with UL and SUL loads is possible and confortable to use frameless packs
I´m agree…. but Im strongly believe that as much more weight you carry on your hips more confortable and less tired your walk is going to be.
And as much weight and walking time you add ..the difference in comfort grows down incredibly fast .-(
carlos
Spain