There is also an issue...a slight one but it's still relevant...of damage. Schrader valves are much more prone to cuts from the valve hole than prestas are. Especially in low pressure situations. On a mountain bike, for example, the high torque and low pressure can lead to tube creep. If the rubber covered schrader valve creeps too far, it can cut the stem. Prestas can't suffer stem cuts in the same manner. The little nut on presta valves, by the way, helps prevent creep in those kinds of applications. Presta valves can be damaged from the pressure pushing the stem out of the rim but schraders can also suffer from this kind of damage.