Your regular cast piston is considered a eutectic piston. The hypereutectic pistons are also cast pistons but "hyper" (over) eutectic is a terminology that describes the metallurgic composition of the aluminum alloy on a molecular level.
Its kind of like mixing sugar in water in the fact that the water can become saturated with sugar to the point it wont dissolve any more sugar and any additional will remain granular at the bottom of the glass as a separate form, non homogeneous. Hypereutectic is used to define the percentage of silicon (primarily) in the alloy. The advantage of hypereutectic is light weight and low expansion but the disadvantage is they are brittle and don't take well to detonation.
Regarding strength, forged materials take the cake. The disadvantage to forged pistons is they have a higher density and internal stress so they expand more.
My negative experience with Wiseco was with snowmobile engines. It would have been a lot cheaper if it was with chainsaws. Unfortunately they were the only ones making a piston for that motor at the time so our hands were tied. It wasn't until later we learned the OEM had another piston in a new sled that was plug and play.
