The advantage to hyper pistons is their weight. They weigh next to nothing and are strong and cheap for what they offer. I actually read an article in hot rod about a guy who only used hyper pistons because he was convinced their light weight offered more pros than cons. He either used them with forced induction or nitrous... can't remember which. Either way, not easy on the pistons. Need to remember that mixture becomes crucial with hypers tho, because they are prone to failure. Knocking, going lean, etc will mess up hyper pistons in many cases where a forged piston (wouldn't be in heaven but) would survive. Compare the purpose of your engine and what you will subject it to vs the cost and power advantages of running a hyper piston. Hyper pistons are generally considered an excellent piston for mild street buildups that will not see nitrous.
Actually, thinking back, I think they offer a thermodynamic advantage over forged pistons too, perhaps because of their alloy or temper... Anyway, they supposedly offer you more power for the same setup (assuming they dont fail) much in the same way that iron heads theoretically give more power for an identical setup than aluminum do (again assuming youre not detonating, etc).
