Re visors, I guess they do look mountain bikey and along with my helmet mirror and handlebar blinkie white light I stick on the visor also, they aren't very aero (reducing my top speed attempts by a few kph I'm sure), but I have to say it's great keeping the sun off your forehead and out of your eyes when riding into a lowering sun.
There are a few times i wish I didn't have one when really down in the drops, but for the vast majority of the time they are great in my opinion. Kinda like driving a car without a sun visor.
I'd very much doubt a visor drops your speed a few KPH. Agreed on the drops, they aren't great when I am pounding something out with my head down, but the other 99% of the time I love them. I don't really care if I look mountain bikey, I am far more concerned with what is effective FOR ME than what "looks" right. They fit right in with my MTB shoes and baggy MTB shorts and unbranded polo-looking jersey on my road bikes
