I went with friction shifters so that I wouldn't have shifting issues in the cold, I heard abut the concept on the now defunct Icebike site.
My bike came with rapid fire shifters, I noticed condensation in the gear indicator windows, I figured if there was condensation in there, that could be an issue in the winter. So I switched to Shimano Fingertip shifters. I have not had any shifting issues in the last two years.

I decided to run a full length rear brake cable after I had issues with the rear brake cable freezing up. Seems to have taken care of the problem.