No, they're quiet. I don't hear anything from them. In retrospect, I would have preferred getting JUST slotted....but... >shrug<
Oh well. I don't really think it matters.... the more holes there are, the less surface area for the pad...so... solid would probably be best. The whole 'dimple drilled/slotted' thing is just for looks; it was ORIGINALLY to help pads disperse gas given off (but I've read that was mainly for asbestos pads, which almost nobody uses anymore), and the drilled holes were to let water into, so the pads wouldn't hydroplane on the rotor (more of a problem with motorcycles).
Basically, get whatever you think looks cooler.
- Rob