Never had any problems with the hub bearings or freewheels in temperatures down to -40 (windchill doesn't matter for mechanical systems, so these are real temperatures). And any issues with particularly thick grease are easily remedied by adding a bit of oil to thin it out.
By the time freehubs were available I had relocated to more hospitable climates. Not because of any consideration for the bicycle's mechanical parts, but because the bike motor's specifications had been established for sub-tropical Africa a few million years ago and preferred temperatures that stayed positive.