I ran single speed for a while, but my knees were talkin' to me on the steeper stuff. The day Hammerschmidt was announced, this was the first thing I thought about. It's so simple and perfect. Most of the time 'round here...when you're talking "need"...you don't need more than a couple of gears for the most part.
The down sides?
Overdrive noise when pedaling forward sounds a little like a muffled CK hub:
It's heavier than a crankset with ISCG, but when you think about the big picture of my application...it's lighter than a crankset/FD/RD/cassette/multi rings/extra shifter