Originally posted by drerka AFAIK, the Pentax D-Range function *does* work with raw, so it does have its benefits.
I suppose I should test this rather than guess, but since I know this to be the case with Nikon, I'll at leas offer it as a conjecture:
What may be happening is that D-range is like other in-camera settings - it doesn't actually *affect* the RAW data, but the fact that you used it may be recorded in the file for use by a RAW converter. So just as cranking up the saturation doesn't affect the RAW data, but *will* cause PPL to crank up the saturation by default when it displays / converts your image, it may be that PPL is simply noticing that you set D-range and reproducing it's effect internally. If you, you'd find the image looking correct in PPL but "wrong" - dark, basically - in most other RAW processors. If you're inclined to test this, be sure the other RAW converter really is processing the data and not just displaying the preview.
As I said, I *know* this is the case with Nikon - a Nikon image produced with D-lighting appears dark in any RAW processor other than one specifically designed to reproduce that effect itself (and as far as I know, Nikon's own software is the only one that does). I'd be kind of surprised if that didn't turn out to be true with Pentax also. But I've been known to guess wrong before.
In any case, what's actually happening is not really in question here - the camera processing is simply fiddling with curves after the a/d conversion, just as is the case with Nikon and the others. The only question is whether it does this in its RAW processing or just for JPEG.