Well I got to uninstall and re-install the sliders one more time, yippie!
This time it was due to the fact that I could not get the bolts that hold the diamond plates installed. There was simply not enough clearance between the bottom of the rocker panel and the top of the tread, to get the bolts to drop through, and get an allen wrench on them.
This highlighted an issue for me, in that the new rails are so tucked in tight under the X, and at a flared angle that I cannot even get a toe-hold on them to actually use them as a step to reach the gear basket or rear carrier. Which totally negates any need for the Diamond Plate, since the slider can't be used as a step... what the point of it, really?
Kinda miffed at myself about this discovery.
I thought that I obsessed over every detail in comparing the various offerings, but this detail slipped past me. I would gladly have sacrificed some clearance in favor of a slider that still allowed me to use it as a step to access the roof.
An expensive mistake, to be sure!