No matter how much attention you are paying there will be unexpected obstacles that you will not be able to avoid. Riding in control means going at a speed at which your reaction time + stopping time allows you to not run into these things. Stopping time will be much faster with a brake then without one. Therefore you will be able to ride faster while still being in control on a bike with a front brake. Since you can ride at a faster speed(especially approaching intersections) there is no way you could be faster(and still in control) overall without a brake. If brakeless riders beat braked riders in alleycats it is purely because they are much stronger riders or quite possibly they are simply more reckless. Being forced to ride more slowly or out of control seems absurd but I guess there could be reasons for it. I really don't care what y'all want to do as long as you avoid me while doing it.