I ride carbon through winter, in fact there is pretty much no steel on my bike which makes it ideal for winter riding, all my bolts/screws/collars are now ti, alu or nylon, cables are all teflon coated, all non drive train parts are carbon, and I use a cheapish 105 steel cassette (which is identical to the ultegra version) that I can replace at a reasonable price and its only 50g heaver than the exotic ti ones.
i think your missing the point of a winter bike which to most sensible people means cheap but decent quality, full mudguard clearence and delibretly heavier than your good bike so that you feel a massive boost when you go back to your good bike in the summer.
not for it to sit in a room when the roads are poopy and components wear quicker!
but then again i still enjoy taking my bmx out for a spin, i know i won't get bored of cycling any time soon!
collect only