this is only my personal opinion so take it for what its worth
i used the SG for 3 years, multiple sheep/goat hunts and packing out elk, im on the slimmer side (150) and the hip belt would dig in from time to time and my spine would occasionally hit the X section on the frame when loaded super heavy. i replaced all the foam padding with thicker stuff and its 100% better, like love it now.
the kifaru is extremely well built (so is the SG) but right outta the box i felt the kifaru is a little more comfier for myself. The kifaru is definitely more heavier like quite a bit more noticeable when the bags are side by side.
id say if i was only planning on doing 7 day and less hunts the SG anything longer than 10 days id probably go with the kifaru.