Red Roberts personally recommended the RST to me (I was thinking RXT) for my KC 496 (666-lb ft).
Easier to depress the clutch pedal. Engaging the clutch is a little more tight, meaning that the distance your foot travels from open to closed is smaller, but VERY streetable.
After 600 miles I hammered it 3 times from a dig. Each time I felt it get more sticky, and it does not slip like the old single disc did.
I recommend it!
E