Or leave the OEM items to keep it looking factory, and fit muffs throughout winter, allowing you to ride in summer gloves and keep the backs of your hands warm too. With muffs fitted I hardly ever need the grip heaters on. Not sure if Val.H still sells them on the forum, but they are well worth the modest outlay.
Some fashionistas think they make you look a twat, I reckon I don't need muffs for that I'm a big enough twat already, but a warm happy one.