Go to your favorite search bar (like Google) and type in blank versus slotted rotors. You will get hundreds of links to forums and even a few articles stating what was summarized on the link I provided above.
Any time you reduce the rotor surface area you reduce braking distance. With the modern pad you don't get gas build up like you did in the past so unless you are trying to reduce rotational mass weight or going for looks slotted rotors offer no real world advantages.
If that isn't enough for you then I would suggest referring to the laws of physics and experimental data you can perform with your 4runner. Get 2 sets of identical pads, one set of slotted rotors and one set of blanks. Preferably made by the same manufacturer. Then perform a series of brakes from a fixed speed with a sample of about 100 on each set and plot the braking distance. You will have a definitive answer and can report your findings here. I bet you an internet cookie you will find blanks do the job, cost less, don't eat through your pads as much, and can be resurfaced, something you would have difficulty doing with slotted rotors. Just make sure you are running new brake fluid and bleeding your brake lines with each change and make sure your rear pads or shoes are changed as well so as to keep your sampling clean.
At the end of the day it's your truck and this is just the internet. If you are happy with slotted rotors then you made the right choice. Just because I wouldn't do it doesn't make me right or you wrong.
