For those interested, here is their site: http://www.rocky-road.com/index2.html
They should be updating it shortly to include the sliders for the R51, and I'm guessing they will cost between $300-400, not including shipping.
Here are the Nissan step rails off my PF:

Lots of plastic! There must be a tiny amount of steel inside these things for mounting & rigidity, but overall they are simple a big wad of plastic.
Here are the supersliders installed, from marginally different angles:




It's really hard to tell in the photos, but there is a very thick square bar (made from hitch stock) that runs directly under the body, which is pretty flush with the sheet metal. Attached to that bar is a thick round bar that is bent at an upwards angle. Absolutely solid as can be. I can stand on the bar and reach the roof rack better than I could on the plastic steps, yet these don't stick out like the steps did. I've run into a few situations in the last 5 months that really made me cringe about crumpling something underneath. I seriously no longer have that fear. I almost want to hit something now. I've seen a ton of rock rails & nerf bars, yet these honestly have to be the strongest things I've ever run across.