You should try them before condemning them as JY hack, or at least ride in a well tuned truck that uses them. I have money for springs and I wouldn't have replaced them. They may be originally for a heavier vehicle ), but simply removing the O/L and the shortest leaf tunes them to work well under a yota pick-up. In no way would I say they only work OK, I would say that they worked excellent for my application. Which is NOT rock-crawling. I used the truck to chase desert racers and to go on week-long + mostly dirt cross-country trips. People moving away from them isn't necessarily a condemnation of them as some guys are never satisfied with what they have. I didn't move away from them, I moved away from the truck that they are under due to rust.
They are fairly flat, so unless you're willing to invert them they don't have the wheel travel that a more arched spring will have. I was willing to occasionally invert them. I used the O/L leaf upside down so that inverting them didn't kink them on the spring perch and I used a progressive rubber bump-stop. They do require a bit more shock damping than other leaf springs. I found Bilstein's 275/78 shim stack to work very, very well with them.