A couple of counterpoints to a very nice review...

My Nexus hub (which is only a 7 speed) does not have a rollerbrake so I don't have that problem. I've ridden the bike through the winter and didn't notice any problem shifting--but the bike is still pretty new (one winter). I don't know the weights of any of the components but I definitely don't think I'm riding on a bag of bricks!

My biggest disagreement is with the comment that derailers are "very low maintenance." I've ridden a derailer bike for 25 years and it needs regular adjustments every couple of weeks. Cables must be cleaned often. The chain would fall off every once in a while, too. That never happens on my Nexus.

I never have to look down when I shift to see if the chain "caught" when shifting. I always do on my derailer bike.

I've also heard the opposite regarding maintenance for an internal gear hub. I've only had mine since December, and haven't done any thing to it, but it is way too early. I guess I'll find out.

Regardless, I love my internal gear hub.