Gloria, there's a nagging thought in the back of my mind saying that somewhere I read that PS H/S adjustment layers increase noise more so than a&b channel adjustments. IIRC, it was something about H/S creating haloing.
Something interesting is definitely happening here. I'll need a little time to think about this, but one thing I noticed, in Photoshop, is that the Brightness of the star shaped noise area changes significantly with the saturaiton adjustment. It seems to me that an HSB or HSL saturation adjustment would change only the saturation.
I found this, written by Peter Lange in a LL http://luminous-landscape.com/forum/index.php?showtopic=11074&hl=# thread: "The Hue&Sat.-saturation slider in RGB mode (Normal blending) combines HSB-saturation with HSB-brightness." So I suppose light-colored halos could be affected? Maybe we aren't just talking noise, but also weird S/L artifacts. How should I know. I am only the son (well, daughter) of a poor but honest fisherman.
I would add that they is ... us! :-)
Mike...sigh. Are you a Pogo reader, perchance?
And Greg...you are relentless on this Wiki thing, and may possibly beat me down, but not without a lot of editing, and not without me knowing what I'm talking about. So it could be awhile :)