Hypereutectic pistons do not expand or contract as much with temperature changes so a "tighter" piston with closer tolerances can be used, this is more of a concern with emissions but you would get less piston ring wear over time because of the consistent size. They are also harder so less material can be used giving the advatages of having a lighter piston that is also rigid, and they can handle higher temperatures because they absorb less heat. Disadvantages... A harder piston is also a more brittle piston, specially at lower temperatures. Detonation/pre ignition or any strong impact shock can destroy a hypereutectic piston instantly where the forged equivalent is more forgiving and can absorb some shock.
In general, I guess a hypereutectic piston is a great piston for a long time and does not wear down much but when it fails, it is sudden. A forged setup gradually wears out over time but does not usually suddenly fail? Again, this is all theory..
If you limit the risk of pre ignition, a hypereutectic piston is a good choice. People with a power adder or higher compression stay away from them for that reason.