11,700 miles on my '03 650 and I've never heard the brakes squeal. But disk brakes on any bike or car can do that if the pads get dusty. The composition of the pads matters too. The more metallic the compound, the more resistant to fade, and the higher likelihood that they'll squeal. Apparently there are ways that the manufacturer can dampen this - from reading the prior posts. That may be one reason that we don't hear disk brakes squeal as often as they did 20 years ago.