Does drilled brakes offer better cooling than the slotted types? TIA

Some say that they do

I dont think that you as a driver are going to be able to tell the difference between the two

Possibly but you sacrifice mass, good for a heatsink, and longevity because drilling
 

often tends to weaken the rotor. With more metal in a slotted rotor you have the greater ability to sink heat.

Drilled brakes vs. slotted types...
 

Drilled brakes look cooler (in both senses of the word), but in fact, the slotted rotors tend to do a better job of cooling the brakes. Furthermore, drilled brakes have a tendency to form small "heat" cracks at the holes and the rotors are more likely to warp as well.
If you think about it, the drilled rotors actually have less metal to dissipate heat, thus they get hotter and have greater difficulty dissipating the heat than a comparably sized slotted rotor.

Thank you all for answering my thread. Much appreciated.

Porsche uses Drilled
 

That's good enough for me. As long as they're brakes designed drilled, and not simply a stock rotor that's been drilled as an afterthought, they should be cooler than slotted types. Slotted allows the brake pad to get more grip and is good when stuff gets on the rotor.

actually i think they are cast with the holes, not "drilled"
 

i think drilly cracks, hence the casting.

sloting/grooves can be cut after the rotor is cast and has had the surface honed

Some are, some aren't
 

You want the ones that ARE cast, not drilled afterwards (some of them).

Better cooling, yes. But DO NOT EVER BUY DRILLED ROTORS FOR TRACK USE
 

Now, Porsche "drilled" rotors are actually cast that way, as 01blackS4 said, and they're OK (though they do crack on occasion, as do all rotors under real heavy use). But actual drilled rotors (i.e. where they take the stock rotor, and drill it) are dangerous. A blue TT at lime rock last year had his front right rotor EXPLODE, taking his wheel and caliper with it, while on the track. Could have been a lot worse - nobody hurt, and the tire contained much of the debris and held that corner of the car up. Please, avoid the aftermarket-drilled rotors. Slotted is fine.