The SD Flex Capacitor pack does have what they call a Lightweight “Y-FLEX” suspension.
While I have gotten used to packs with the large mesh pocket on the back, and might miss that feature. I actually thought them quite weird when I first saw packs starting to use them.
Considering this pack is partly a leap of faith in Andrew Skurka’s judgement. While a lot of LD hikers are opting for packs under 2#. And following thee herd that a large mesh pocket is necessary . Andrew Skurka has done hikes of 6k to 7k miles. I think he learned some things about pack choices and desirable features while walking that far. Of course - Whether he would choose this pack for a similar hike remains to be seen.
This pack is about the same weight and capacity of my Osprey Exos 58. Both are approximately 2.62 #.
About 1.2# heavier than my Gossamer Gear pack. A Mariposa Plus, I think. I’ve had it so long I’ve forgotten the exact model name. I got it , I think, late 2008, it was when they were changing the shape of the internal frame. When ordered it had a straight u-shaped frame. I had to call Grant about something just after getting it, and he said - hey, we are changing the frame to having a slight s-curve, would you prefer that? So I exchanged them, no charge. The newer Mariposa packs are a lot different. Mine is like the one on the left in this picture.
The old and new models are compared in this blog post:
https://blogpackinglight.wordpress.com/2012/07/05/gossamer-gear-mariposa-2012-rucksack/
Anyway, the point being I see the advantage of going with a pack that is 1.2# lighter.
My Marmot 40 ˚ sleeping bag 1.9# : OES Tarp .977# : WB Blackbird hammock 1.55# : WB Yeti UQ .96# : Neo Air pad .893# : Spear pad extender + pads .403 # : Montane Featherlight jacket .265#.
The 1.2 # difference could make way for additional clothing. Or just save 2,000 ft-lbs of energy walking to the top of a 2,000 foot hill. That’s about 3 Snickers bars. However, I do think the heavier packs are more robust. 
For years I’ve used my sleeping bag more like a top quilt than sleeping bag while hammock camping. Recently I ordered an actual top quilt from Paul at Arrow Head Equipment. Apex synthetic 25˚ rating at 1.5# weight vs my 40˚ down sleeping bag. Not yet used it camping, just a couple of day hikes, set up the hammock and try it out for half an hour. Hoping it works out.
Just saw the SD Back Country Quilt and also thought it has some interesting features. The built in hand pocket and hood seem like functional ideas - Though I’m not much for camping out when it’s so cold I would only want my nose and mouth exposed to the cold. I like looking at the kind of cold from the warm side of the windows. 
https://www.youtube.com/watch?v=vYe4Alm9MiE
