Slotted and or drilled rotors have their application, unfortunately it is not on the street. Like Eddie said all they really do in a street application is drastically shorten brake pad life. How are the brakes on the boat trailer?
I am using Wagner SevereDuty Brake Pads (Carbon-enhanced metallic) with OEM rotors (on the front; drums on rear) and have been satisfied with the setup. I do a fair amount of mountain driving and this is a great improvement. The pads take a couple seconds to warm-up, but once warm, they bite hard and don't fade (better than OEM and ThermoQuiet, IMO). I haven't noticed abnormal rotor wear.