Probably because asym packs are not attractive with that growth hanging off one side. I'd put money that if you look at their sales history, that would even show up in the data. ST 6900 fixes this, but at that weight you're basically within a pound of a Kifaru frame plus bag of your choice. (Even the 6300 @ 5lb-8oz is pushing close to a Kifaru setup .. my Tactical frame + giant EMRII bag is right about 6.5 lbs, and much larger.)
I really wanted to try an SG X-curve, but their bags seriously do not do it for me. I've used a LOT of bags, and being in SAR I see all kinds from all sorts of differnt mfgs, dyneema to cordura1000, but SGs are just head-scratchers, like 'wtf were they thinking' and 'wow, those are some ugly packs.'
But that frame is tempting for sure ...
Also, the R3 line... .who thought THAT was a good color scheme and angle to shoot(!) those bigger packs? I mean, really....
USA-made lightweight Stone Glacier packs on KruX, XCurve & R3 frames are ideal for day hikes, multi-day hunts, military ops & alpine expeditions.
www.stoneglacier.com
Cheers,
-mox