My experience with the SRAM Spectro S7 has been fairly positive. I put it on a commuter
last year and put ~1000 miles on it. It has worked well for me, although I have also
noticed inefficiency and noise in the lowest 2 gears. I'm sold on the concept of internal
gears for an all-weather commuter, but would consider trying Nexus next time around.

For my type of commuting (27 mile r/t with mostly smooth trails/roads), I don't see
any great advantage to a dishless wheel. I just don't stress out my wheels enough
for that to be a big deal.

I've also done some commuting on my singlespeed and found it to be a bit strange.
The gearing necessary to tackle the big climb on the way home is low enough that
I'm spinning a bit too much for the rest of the ride. Even though I feel really inefficient,
the amount of time lost on my single speed is actually quite small.

baker