If I had to replace the bike I have now. I'd get a Surly 1x1 outfitted with a derailluer or a IGH. That thing has all the braze-ons you'd want. Plus it'll fit disk or cantilever brakes. And best of all, it'll fit either 1" tires or 2.75. Awesome snowbike ! This is the website where I first saw one.
http://mplsmtb.blogspot.com/2008/11/...-mans-pug.html