I run aerobars on my road bike which is also my commuter most days. The stem is also flipped to give me an addition inch or so handlebar height. My areobars are two separate bars that go straight out and have fixed elbow pads (i.e. don't flip up). The take up mounting room but I mount everything on them instead - bell, air horn, blinky, 2 lights, and cyclometer. My available hand positions are drops, hoods, aerobars, stiff arm on aerobar elbow pads.
They do stretch out the back and take a lot of weight of my hands (the primary reason I bought them). They do help my speed and are particulary nice in headwinds. They are not very stable, though, and I only use them for on straight smooth surfaces.