One of the advantages of IGH is that the drivetrain can be fully enclosed. That's what you'll see on just about every bicycle used for transportation outside of english speaking countries (and one of many reasons why they don't use derailleurs). That will take care of about 90% of winter problems. Next is to keep cables working which for me means dripping a bunch of oil in the housings about once every 5 years. We've ridden through MN and other winters with Nexus 8's, SA 3's, and N-360's with zero problems. Which reminds me, I think I'm a couple of years overdue on cable oiling. :-)

As [MENTION=90453]tjspiel[/MENTION] mentioned, an oil bath helps the Nexus' a lot.