I'm happy to read all the good things about 4Runner towing capabilty, but I have heard and seen opposite of these.
I bought my '02 4Runner with 58k miles on it. When I bought it a found a towing receiver in the rear storage, and was told that the previous owner did some light towing. 6k miles later my transmission went out. I was told by the dealer that someone did "A LOT" of towing with that car, and that the transmission looked "abused". I have a new transmission now with a new 60k warranty. But at that time I've called everyone, and no matter who I talked to they all said the same story of how Toyotas are not great towing cars.
While at the dealers, I sat next to a guy who was waiting for a third transmission replacement in his 140k mile V8 Tundra, he said he used it mainly for some trailer towing.
I've got nothing to tow, but I don't know if I'd pick a 4Runner to do it with if I had. But then again I'm still angry about my transmission replacement at 65k miles.