As mentioned more than a few times, I've been trying to ride clipless this winter...in a non-specific (i.e. cheapo) winter shoe. I had a "theory" that a generic shoe would work given a arge enough size. Here's why it doesn't (below -10):
A) Metal hardware without enough insulation and insuffucient sole. Theoretically, a large enough shoe could layer enough insulation without compromising foot circulation. While this may be generally true, the metal conducts cold much too well in these shoes.
B) The plastic(y) sole also conducts cold much too well.
The plastic that makes up the sole becomes too stiff at around > -10 and feels practically like metal.
C) The thin leather outer provides no wind protection. Even with goretex covers the wind and cold find a way in after an hour or two.
Overall, I still believe a clipless shoe can be a good winter product if the sole were better insulated with a softer rubber, like vibram. I wonder about carbon for clipping, metal just sucks in cold. Of course, to have the room needed in these I would need to go up about ohhhh 100 more sizes. Lakes are basically the only winter shoes I've heard stand up to the cold but it looks more like a hiking boot which means xtra weight. Hiking or pushing a bike many miles in my ultralight lobbens versus a hiking boot is much easier on the old body (I've done both).
I am in platforms now since the temps are getting lower than -10 and using the lobbens. While they are comfortable I definitely miss the clipless. Clipless certainly feels more balanced in the legs (pulling up and pushing down) and seems to add more horsepower as a result.