There are at least a couple of fellow couriers here in Toronto who ride all day with no brakes AND no foot retention. I have no idea how they stay safe. Personally, I keep my brake on just for that once-a-year "OH ****" moment, like when you're cutting between stopped cars at a red light and some pedestrian pops out from behind a cube van.

I was once in an alleycat and a minivan took a left turn in front of a racer who was two metres ahead of me. He had no time to lock up his pedals and went right into the front side panel. He was fine but he left a giant greasy face print on the passenger window and took a ride to the hospital in a neck brace. That convinced me to hold off on removing my brake for a while longer.