Jason, I have made a Ray-way, but not a G4. I've made packs, tarps, tents, and quilts/sleeping bags. I think quilts are the most tedious to make, but packs are the hardest from a number of steps perspective. Ray's pack kit comes with nice instructions. The final pack should weigh under 10 oz. Six pounds of gear would fit nicely in the smallest Ray-way pack. That's the size I made (original size). The original kits don't have hip belts or sternum straps. My understanding is the newer kits add these. I personally like the old style. I often hike with the pack hanging from one shoulder and never miss the hip belt. I found the pack to be extremely well built and strong from a design perspective.
This being said I have heard folks having great luck with the G4. I would say if you have sewing basics under your belt either kit would work well for you. I'd look closer at what each pack has to offer compared to your needs.