It doesn't seem to just happen with really sharp edges, Martin, I've noticed the difference with the RDM on simple fake stones shader's displacement as well.
Just a clear explanation on the more obscure setting's functions would be adequate, of course, the subdivision settings aren't actually meant to be out there yet but there are many other areas where I find contradictory results and outcomes, for example, what exactly is the relaitionship to the IU functions in line with the smoothing tab(and compute terrain smoothing), so far, it's been officially said that those settings all relate, but not how they do. Similarly, the noise variation methods in probably the most common shader node(power fractal), even in the online documentation, is still missing that information, the node reference for the PFS seem to be the very same ones that Frank wrote around 3-4 years ago and as yet, hasn't been updated.
I think it just comes down to the old story that everyone already knows, there is no solid documentation and labelling of many features. Many of us can work things out by repeated trial and error methods but, not everyone has the time to just sit and render back to back tests checking one setting against another, I think people want to be able to read that this slider does this, that checkbox does that, is all.
