Awesome shader!
So there's two aspects that seem to be driving how the rock and grass combine. The first is how the grass maps are handled, so that they'll tile according to the geometry.
It uses the Texture Cooridinate node hooked to the Mapping node with Point selected. Scale changes how it tiles, and seems to work the opposite of Poser in general. As far as I can tell, this texture is just for the grass, and the stone texture is purely procedural. But I'm not absolutely sure.
The slope detection is, as far as I can tell, this group of nodes
Maybe reproduce the first in a grass texture, make a stone texture, then use the second in a shader to control a MixRGB node with the grass and stone textures plugged into it? That's my first thought, at least.
Cycles isn't designed for photorealism, just a better balance and range between realism and stylization than BI. Brecht's intention was more power for realism _and_ stylization (at least, that's what he said). It also works with Freestyle. I think it even works with Freestyle in ways BI can't now, but I'm not sure. I know that BI is no longer being developed, and Freestyle and Cycles have had features added fairly recently, but I don't use BI and have only played a little with Freestyle, so I'm not certain. But generally speaking, everything in Cycles is designed to let you add _tons_ of stylization any way you want. There's a lot of power I'm not sure is in BI. Checking, yeah, there's actually more ways to stylize your shaders in Cycles, because there's more info you can base things on. For instance, Hair Info, Fresnel and Layer Weight, Light Path, and Object Info.
I actually wish the Cycles team gave photorealism a higher priority. The quickest and most versatile way to generate caustics is
to fake them.
I can see how if you're used to fake reflections/specular, BI will probably be more familiar when it comes to highlights. And if you're mostly used to using the root node, it would make sense that the Material and Extended Material nodes seem more like Poser.
For me, though, I find Cycles more like Poser than BI. For one thing, the core shading nodes are more similar. Since I generally avoid using the diffuse and specular shaders internal to the FF root node, I'm very comfortable with selecting the shading nodes I want to combine. But for me the biggie is that there's no distinction between textures and shaders. BI was designed for a time when efficiency was the big issue. So it's designed for shader and geometry independent tiling textures you'd use throughout your scene. I'm much more comfortable with everything working as it does in Poser, where materials are combinations of shaders and textures working together.
But the speed issue is a biggie. I haven't clocked BI vs Cycles on my CPU, but I'm not surprised you find BI faster. Cycles' speed varies depending on the version. Sometimes it gets slower when they add a new feature or tweak something. Then it will get faster in a version or so.
You know, I've been focused on Cycles tutorials so long I don't think Google even sends me BI tutorials when I look. Then again, it may be the type of stuff I look for. I think BI's procedural textures are still more full-featured than Cycles'. Which is great for landscapes and such. I haven't been looking in that area, so I wouldn't have seen BI tutorials for landscapes. I will be soon, so I may see more BI tutorials in the future.
Yeah, you can do so much with Blender. And any 3D studio app, really. I just ignore most of it, and focus on modeling, mapping, modifying and morphing, sculpting, texturing and materials, cloth sims, particles, hair, and rendering. Which, dauntingly, is still less than half of what it can do, and not yet all I want to do. Anything you can do to dip the needle toward getting stuff done is a smart move.