"safer without brakes" argument (and inherent logical flaws) aside, I hate these things with an incredible passion. I had a lovely discussion with one of the designers at a seminar at UCBerkeley by the end of which he was agreeing that the thing wasn't really capable of replacing car miles (due to speed/carrying capacity/inability to lock the thing up/etc) and basically was only replacing walking and some biking miles. Good thing there are plenty of rich americans lazy and fat enough to buy them.