Yes indeed Martin although there is one note with all this.
You based your findings with the use of Lightroom 2 default settings so anyone not using the default settings or using another program would get different results.

This is one of the problems with RAW, nothing is fixed so even if the camera makes a histogram from the RAW file it might not be the same as you would see on the computer and so even between programs there is an difference.

Every software read/process the information in the RAW file in their own way.

Was expecting a revelation Martin but all is just like you told, thank you for your time.
Hopefully George isn't laying down since he probably won't be able to read your proof then.

Just tested everything with my camera and the green button does do nothing on his own with any of my modes

I don't have iso settings under one of the wheels since I've the EV compensation on that since that is more logical to me. So the green button does not make ISO go to auto then.

If I want to change the ISO and this works in any mode except Sv for the obvious reasons, I simply press the OK button and use the front wheel to change the iso to a fix value or press the green button for auto, just like I said earlier.

Does that fix the problem for you Stu?

That would be interesting
The final answer on this mystery.

George I'm going to comment on your comment, spend the whole night thinking about it.

Okay here is the deal.
You're right with everything if only one assumption you make was right.
The thing that isn't right is that RAW files don't have colour profile, so no sRGB, aRGB or any other thinkable thing they just don't have it.

With this You can answer your question about the histogram but first what does mean for your workflow.

Silkypix opens the RAW file and makes assumptions really, with Adobe you can control that and even assign a colour space and I'm quite sure Silkypix will let you do that as well.
I've no idea how Silkypix works, haven't played enough with it, Matt can probable answer all your questions about that one.
So far my understanding goes it's best to select the widest colourspace you can since silkypix doesn't need to compress the colours in your RAW file so that they will fit your selected colour space, it's most likely the best to do that in the output stage.

Now the histogram question.
I've also no idea what Martin wants with the -2, hopefully he will explain that later.
Although I can tell you why it's better for the histogram to shoot in aRGB.

Like I told earlier, RAW files don't have a colour space so that means that they will most likely capture colours beyond the sRGB or even aRGB space.
Although the thing is that the camera use the JPG preview to create an histogram for that photo and that JPG preview is created with your JPG settings and as aRGB is closer to the colours the RAW file have it's better to use that.

You're always welcome to come

You get the best results when the darkframe is taken right after but if you need to take many exposures you can make one darkframe and then later on the PC do the darkframe extraction.
Although they don't give you that option with the newer camera's.

Some here already contacted them about it and well they have done something. They seem to have improved the auto settings, just don't know with how much though.

Sorry to spoil your hopes but I don't believe you can turn it off with the K20D, you've the options ON & AUTO, so no off.
I knew some star-photographers here were complaining about that.

Sorry for my misunderstanding Martin, thank you for clearing that up.

Simply to add.
If you've the new firmware installed, and you press the OK button on the back you can change the ISO as well with the front wheel or the green button. This works in any mode I believe.