Up in northern Sweden we have started to get some experience of accesory high beams (only used together with the ordinary high beam). Today there are LEDs that are much more powerful than ordinary big extra headlights, but there are some problems with them in the winter. They run a little bit too cool, frost and snow do not melt of the glass making them useless. But some have made successful installations behind the grill where they do not see much snow, and in slow speeds also may benefit from some ICE-radiator heat.
In the winter we have also seen this regarding tail lights, especially on big trucks, big semis, 18-wheelers and so on, the rear end becomes like a brick wall of snow and ice. Old ordinary 15W tail lights will melt the snow on the glass, exept in extreme conditions, LEDs do not.