The G2 has the aluminum stays. First thing I did was bend them to fit my wacked out back..... I have a funny shape. Must have been scrunched inside my mothers womb......
E'stock has some very good fitment video's on their website BTW.
I think the comments about suspension, lack of of the G2 gunrunner comes from not fitting it properly. It has to ride on your hips not on your back or shoulders. I have no issue with mine and I only carry the rifle in the scabbard in transit, in stalk, I'm carrying the rifle in hand or slung on my shoulder and the G2 will accomodate my land cannon 338 Savage with a 5 round magazine, harris bi-pod and a big scope, no problem, those usually it's carrying a 308.
I haven't really loaded it down yet but it's done well for the tasks I've used it for and you can really compress it against the scabbard when running light.
I would recommend getting the external raincover whichever pack you decide on. The material the packs are made from is water resistant, not water proof and the rain covers are reversible, camo one side, hunter orange on the other.
I'm very happy with mine.