Okay, second render finished earlier than I'd expected, so I can post it now before I head off to bed (hooray!).
I'm quite happy with this one, I think the forground looks a little better because the lighting coming from the left gives the stones shadows. I take what Old Blaggard says about the stones, but to be honst, I'm not really confident about messing around with the fake stones settings other than size and density, as I'm uncertain as to the effect.
Anyway, thanks again for you comments, and grateful if you could give me your thoughts on this version.