Kowee, thank you! That's some really good advice!
I'm posting your version here, because I like it:

- The top right corner had been bugging me for a while. I was excusing that and the "specular" patch because of a very close light source. That you can't see, obviously. Still, the more I looked at it the more I knew in my heart it was wrong. I fixed the corner in a recent edit, and you're right about the dots. They can be less in-your-face. I will experiment.
- Those specular highlights on the front top corner really add some life. I thought that the other times I added similar highlights as well. I need to use them more.
- The lowered section on the top looks great! Definitely adds more rockiness to the piece.
- The dark brown part... A lot of what I've done here has been trying to imply shading without banding, or texture without complete coverage, or lines without continuation. The dark lower sections are an attempt to darken the base into shadow with something that has a reason for creating an outline. In this case, some kind of mould or moss.
It's also a complete rip-off of the styles of some artists I admire. I guess whether it makes it into the final piece depends on whether I put it among grass or among other rocks and shadows. I like yours, it looks cleaner without, but when I see other works using similar details I appreciate them. Maybe I don't have the flair of my idols! Maybe it needs context. Maybe I'm applying it inappropriately.
There's a lot of lovely little details you added, as well. I'll be spending some time analysing those!
To attach an image, right-click on it in Imgur, "Copy image address", then paste it into the Zooming Mona Lisa control (underneath the Bold B).
Thanks again!