Well, I have been working on a similar style pack for myself. I bought some MOLLE suspension and a frame and then ditched the frame for an old aluminum frame I had. I used it for two trips, one with my sons, more than 50 lbs and only 2 miles, and the other being 10 miles and around 40 lbs. Both trips showed how comfortable the MOLLE straps were on the pack. Here is a picture of it when I really loaded it with 2 sleeping bags, a 2 man tent, my hammock, and clothes for me and my son, plus food for 3.
Because I like the way it felt, I wanted to see and make one a little smaller, but still use an external frame and the MOLLE suspension. I was able to buy another aluminum frame from a thrift store that weighed in at .88 lbs. However, when I weighed the MOLLE suspension, they were very heavy. The hip belt was 1.17 lbs, and the shoulder straps were 1.43 lbs. So with just the frame and suspension, I am at 3.5 lbs. I really like the design of the suspension, so I am planning to sew my own with lighter material (not 1000D cordura). I just finished another water bottle holder this weekend that attaches to my hip belt. I like it on the hip belt more. It is easier to get to. I also want to make a front pack, similar to the Kifaru Koala.