I wouldn't say it's all that much more expensive and I have those same questions. Along with, is there more protection from using the JD product as compared to Dextron 4? Which is what I usually use.
Protection "against what" that any of the Dexron doesn't give? I'm not trying to be smart, I'm just trying to figure out why it seems someone is always trying to reinvent the wheel. From selling auto parts.....including hydraulic fluids, I remember John Deere fluids being quite a bit higher. But I don't remember "which" JD fluid that was, either.
What I'm gettin at is, if you're doin somethin where the transmission will burn up using Dexron, IMO, it's gonna do the same with any other fluid. I just "don't see" fluid being the "one thing" that saves a transmission.