I recently replaced my pads and rotors and researched the issue more than any sane person should...as I tend to do with everything. In short, the consensus seems to be that the only advantage to drilled/slotted rotors MAY be on very high performance track vehicles which regularly undergo lots of heavy braking at high speeds with very little time to cool off, which I could imagine could also translate to a vehicle that does lots of towing with heavy braking. But even then, it's unclear there are any advantages. The slots/holes can IN THEORY help them cool off faster. But they also result in less surface area for the pads to contact, which may require more braking force, possibly negating the theoretical advantage in cooling. But they're also lighter weight? Yes, but that also means less thermal mass, so again, we're back to the world of trade-offs that probably negate each other.
That's all fine and dandy, but all in the realm of theory. Independent testing shows little or no difference between slotted/drilled rotors and standard rotors when using equivalent pads, calipers, braking pressure, etc. It does show that drilled/slotted rotors cause more noise and cause brake pads to wear faster, meaning they are also much dirtier, Re-profiling them (if you're into that kinda thing, I'm not) is more difficult and they're more expensive to begin with. I'm not sure about the quality of Toyotas OEM rotors, but I know that most legit mechanics will recommend AC Delco, Raybestos, or similar standard rotors, preferably the highest quality you can afford, and Akebono pads are generally considered the best, although Raybestos, Bosch, and Powerstop are all up there too in the same league.
In fact, outside of manufacturers websites selling slotted/drilled rotors, or "racing" forums (where, let's be honest, looks often triumph over ACTUAL functionality) it's tough to find many people advocating slotted/drilled rotors over standard. Yes they are out there, but tough to find, versus the "consensus" seeming to be that traditional solid rotors and good pads are the way to go.
I have found this forum to be a wealth of knowledge, much like this forum, but more tilted towards serious mechanics who nerd out on specs, empirical data, and a vast wealth real world experience actually working on vehicles professionally and as a hobby. This thread kind of summarizes what I found on multiple other blogs, forums, review sites, etc. which is why I went with AC Delco gold rotors and Akebono pads.
I've been told by a few people that on modern cars with ceramic brake pads, there's really no benefit to using drilled or slotted rotors any more. The reasoning is that ceramic pads don't outgas or dust up like semi-metallic or organic pads did, so the slots/holes aren't removing any gases or...
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That said, if you're noticing a marked improvement in your braking performance, that's great! But keep in mind that could be a function of simply changing from old pads/rotors to new ones more broadly. You might've found that you would've got similar or even better results had you gone the "traditional" route. Either way, you do you! Glad you're happy with the new safety clamps!
