Good for you but that has very little to do with my point. So you where able to podium with only a front brake. You have my congratulation for being very strong. It has little to do with general riding though. Yes you can ride alot of trails without using your back brake... but you have to go significantly slower parts of them and there are plenty of trails I have ridden that you simply couldn't ride all of without two brakes. These sections are the ones where you would be most likely to not be able to apply the smooth pressure needed to keep your rear wheel from breaking free too. If you ride at a speed that allows you to keep complete control over your rear wheel at all times fine. I haven't ever ridden with you I have no way of knowing. I doubt however there aren't times that you are unable to apply pressure smoothly enough to keep your rear wheel from breaking free. If so you should have a rear brake for those occaisions.