Well, brakes are 100% personal preference. Most people who actually have both front and back ride flatland. Not all of them, but most. Rear brake is generally just to be able to actually stop, street, dirt, vert, whatever. I personally don't have brakes, and its mostly a build up factor. Without brakes, I can't stop as easily on the run-up to a trick, so I might as well give it a go. A lot less puss outs. And there aren't a whole ton of geo differences between race frames and any others. Its mostly a material difference and a part/setup difference that makes the bike.