I put Raybestos Superstop drilled/slotted rotors on my wife's Jeep GC. Drilled/slotted rotors can look cool and OK for the street but I don't think I'd want do any serious offroading with them. I've heard that running them through really cold water by crossing a good sized river or stream after getting them real hot decending a trail can create cracks around the holes. Here an interesting article I google'd up on the subject http://www.superchargersonline.com/content.asp?ID=98

For an offroaded truck the slotted only ones may be OK. IMHO for more steet over trail performance the vented rotor would be a even better upgrade for your toyota. Check them out at http://www.trail-gear.com/brake.html. You can also get some V6 calipers as an upgrade if you got an old truck like me.

I'd stay away from the drilled/slotted rotors. Pesonally I perfer the Toyota factory solid rotor design. This rotor design is trail tough and stops more than good enough for me. Plus the price is right, just bought a set of Raybestos PG Plus solid rotors with pads to match at Rock Auto. Here's a 5% discount code 414077336328 that you can use if you want to go and check them out.
http://www.rockauto.com/catalog/catalog.php