The recent brake shudder thread reminded me of this question that I've had rattling around in my head.
Are brake boosters useful and/or common on cyclocross bikes? I have one on my old mountain bike. It doesn't weigh much; greatly improves braking, and I've never known it to collect much mud. Heck, it was even cheap.
If disk brakes are not legal, then I'm guessing that having better brakes is a great advantage. Well, common sense tells me that, too.