I have only used skiis with my larger planes and powder belly landings for my 1/2A stuff. I would not recommend flying with floats from bare ice as it is very abrasive, but snow should be fine.

As mentioned, cold hands is the biggest concern. Buy or make a transmitter mit. (a big square insulated cover that fits over your transmitter) Trying to use even fingerless gloves is awkward and flying in gloves is madness. My best friend is the little glove and boot warmers that heat up when you expose them to air. They put out a lot of heat for over an hour and make it much more enjoyable.

Also too, remember to reset your carb to the colder (denser) air or the engine will run lean.

I have also noticed that wings seem to generate surprisingly more lift than in the dog days of summer.

To me flying in the winter is a necessity since it is a good portion of the year!