I've been riding the Shimano Nexus-8 since about March of this year putting ~1000 miles on it. No issues thus far - I love the ability to shift while stopped and not having to worry about the chain falling off. I have changed the back tire mid-commute with no real difficulty, but I was prepared with a 15mm wrench in my bag. Also, I thought I have read somewhere about a way to "weather-proof" the Shimano hubs - may have been to pack grease between the rubber seal and hub shell... I'll see if I can find it again.