You're right in that you can use your skill to modulate the brake action but they can take you by surprise if you're not ready for them. They're "self energizing"...the forward motion of the rim helps to pull the brakes inward due to the angled pivots. The amount of time and effort it takes to lock up is swift and easy. As Zukahn points out, here's very little adjustment you can make apart from the initial cable length and adjusters on the hoods. The straddle is a fixed length and the brake pads are uniquely shaped to suit the brake arm force. This over-sensitivity is intrinsic to the design.