The more I see of them in use by "regular" riders in the neighborhood, the more intrigued I've become. A lot of people site a number of reasons for liking them, "more stopping power", "better modulation", better performance in the wet", etc. While that certainly piques my interest, I've got to ask, "Is the different in braking performance worth the cost of n+1?" As far as braking "power", I can lock up both wheels easily with my existing rim brakes and since I'm a fair weather pavement rider almost exclusively, performance in adverse conditions isn't much of a concern.
Mind you, it's been a looong time since I've bought a bike and the idea does excite me. So go ahead... Convince me