The Six Moon Designs Fusion 65 was the pack I chose for my 8 day backpacking trip to Peru. At 65 litres it allowed me the volume required to carry the 10 days food required. At the start of the trek I reckoned I was carrying around the 35lbs mark (16 kg), which is the upper limit of what I want to carry on any trip.
I have to say that I was pretty happy with the comfort even at this weight. The pack was designed by Brian Frankle who founded ULA Equipment and you can see his design influence, like the ula packs the focus is on having a comprehensive hip belt with an effective method of transferring the load to it. Factors which we agree are the crucial ones when designing a pack.
When you buy your pack you choose an appropriate sized hipbelt and shoulder yoke. The hipbelt is easy to size as its dependent on your waist size. the adjustment of the hipbelt is via two straps on each side, on the top and bottom edges, an arrangement which means you can fine tune the fit to match your hips and you can vary the pressure points slightly.
The shoulder yoke comes in 3 sizes and another velcro arrangement allows you to vary the back length to suit.
Transfer of the load is achieved using an internal plastic framesheet stiffened using an aluminium bar, and this works very well. The only small criticism i have of the comfort is that the pack seems to sit off your back a little making the weight drag, perhaps a longer thinner design would have sorted this out. The smaller 45 litre model is perfectly sized in this respect.
Feature wise the pack is made of pretty tough material and Six Moon Designs have researched the stretch mesh settling on one which is tough as well, this is a vulnerable part of many rucksacks but 6MD have got a good product here, after my trip there's no sign of any early damage.
The pack has a rolltop closure which keeps weight down but you don't get the flexibility of a lid with pockets and such, organisation is easy though because of the huge outer stuff pocket, side stuff pockets and hipbelt pockets.
The Fusion packs are lightweight, tough and capable of carrying quite heavy loads comfortably, with plenty of pockets to keep you organised they come highly recommend.