Uh, let's see...
Just wondering what constitutes a single speed. OK, so this isn't it.
What about something like that Rivendell with two chainrings? What about that white bros setup with the dual dual thing? And, OMG, pray for those fixies when they lose their secret single speed derailleur-haters club card by showing up with their fixed 2sp hub.
Hee hee.
I've ridden single and fix, and would say that this setup rides more like a singlespeed than a bike that shifts. If you read a bit, you'll find that this was just an intermediate step--the bike ended up with a front brake as well. Accomplish? Get a bike on the road with pieces and parts I have on hand on a weekend when I couldn't get to a hardware shop, let alone bike shop. There wasn't a lot of noise due to the derailleur. Would the drag of an aftermarket tensioner be any less?
Next time I'll post in Alt Bike for something like this--sorry about the wasted bandwidth.