Weight wise they are on par with griffons and lighter then FKS. If it was me I would compare the STH2 13 against the Attack 13. The Attack is a really good binding at a great price. I would say the griffon is equal to the attack but with the attack being cheaper I think the attack wins.
I would only go FKS if you have friends in shops who can get you parts. They are a great binding but the lack of support from rossi in getting spares to shops really lets them down unfortunately. But if you have never damaged a binding and are not hard on gear, then FKS may be worth a try as they are a solid binding. Maybe look PX 12 instead though, but then I would again go STH2, Attack or griffon before a px 12.