Right now I'm sitting at home waiting for the UPS guy to deliver the new wheel set sent from Dallas last Friday. The rear flip flop hub has both the SS and FG cogs. My bike just came with the SS cog. It's also the bike I rode my first century on. Distance should not be an issue.
The ground is pretty flat here though there is a bit of wind (even the geared riders on my century ride were complaining about the wind that day). Still I like the simplicity of the drive train. Having less to go wrong equates with greater reliability for someone like me that tends to ride hard and put my bike up wet and do maintenance every one or two weeks (not the greatest of wrenches either).
Also being strapped into the pedals and not having any gear choices to shift to has made me a better rider. My cadence has improved and where I used to shift down for the few inclines I do ride I now tend to increase cadence to gain momentum and climb more quickly rather then shift down to a slower gear (probably wouldn't work too well for those long grades though).
Over all I'm glad I went with the SS choice for a commuter.
By the way, I'm no uber cyclist or hipster. I'm a 50 year old clydesdale that had high blood pressure (last time I checked it though it was fresh from a 30 mile ride and it was dead normal) and a left hip that bothers me when the weather changes.