Slots and holes both do that same thing. They offer any pad-heat generated gas a place to go. Most modern pad compounds don't outgas very much. Older pad compounds do. Something that slots offer that holes (when done right) don't is a mild 'cutting' edge to clean glazing off of the pad surface.
Something else to think about: slotting, and to a greater degree drilling, actually reduce the surface area of the rotor under the pad. This means for the same heat generation the rotor & pad will heat up faster. Granted, it may cool faster too. One way you can take advantage of cross drilling is to use a pad that otherwise might be a little too high temp for the application. All pad compounds have a temp vs. coefficient of Friction curve. Findind that pad with the best curve for your application will yield far, far better results than throwing money at gee-gaws like slotted or drilled rotors.
It's pretty rare that rotors warp anymore. B4 you do anything, have a brake shop take the lightest skim cut they can on the rotors. See if that doesn't clear up your pulsation. Some compounds and rotor materials build up pad material on the rotors unevenly. Don't really know why, they just do. That uneven build up will give you the pulsation that makes most think the rotors are warped. To give you an idea of how small this varience in build up is, you can't measure it w/o some extremely expensive tools. A micrometer MAY catch it, probably not.
TS
"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
