I've been researching bikes with Alfine drivetrains such as Giant Seek 1, Kona Dr. Fine, Jamis Commuter 4, etc. All of those bikes are hard to find in my area. (To be fair, I think the Giant cannot be found primarily because they're between 2009 and 2010 model years.)

I also run across a lot of nice looking bikes with Nexus drivetrains, but I tend to shy away since I'm worried the Nexus is just a low-cost version of Alfine. Of course, I don't really know. Can anyone explain what the major differences are between these two component groups?