Today I tried commuting on my road bike, carbon fiber, Campy Chorus, Easton EA90 wheels..., It's a nice ride. Usually I'm on my old Trek MTB. Was it any faster? The ride in was actually really slow as I was being very cautious. I also had a laptop in my messenger bag, and it wasn't quite hanging right on me. Going up hills was not as fast as it usually would be, riding on the streets felt treacherous
The way home felt better as I left the laptop in my office and I probably shaved about 10 minutes off the ride. Still, 50 minutes to go 10 miles is hardly blazing fast. Once back in Brooklyn I was able to cruise a bit, I was doing 22-23 in Prospect Park on the flat, and hit 32 going down the small hill. The Manhattan Bridge was also much easier than on my MTB. I won't do it again though, it felt too uncomfortable.