I have done it before with great success. Don't mind a decrease in breathability - I'm convinced that snow, rain and slush absorbed by leather soles would make my feet more wet than the extra sweat that may stay due to the rubber.
My cobbler successfully re-soles C&J shoes and he is the best in my little town of half a million citizens, so no worries that he would ruin the shoes. Besides, we're talking Â£180 Alfred Sargents here, unlike C&J handgrade or EG etc. which are roughly twice as expensive or even more.
I know that many shoe connaisseurs would never put rubber on leather, but one has to be a bit practical when the weather conditions are bad.