ISO and the HDR Photo

One of the final effects of ISO settings I need to see is how the 'noise' translates to my HDR workflow.  Usual HDR processing will create some noise - and the software will also remove noise as well.

For these comparisons, I'm using the full image.  Again I'm showing the close up subject and the distant subject.  I'm using Photomatix Pro 5.1.1 with the Painterly 3 preset.  In my opinion, that setting brings out a medium amount of noise.

Close up Subject:

ISO 200  f/Stop  22   1/60

ISO 800  f/Stop 22  1/320

In this shot - I really can't tell much of a difference between the two.  Experience tells me all the 'noise' can be cleaned up easily in both shots.

For the distance subject:

ISO 200  f/Stop 29  1/40

ISO 800  f/Stop 25  1/200

ISO 1600  f/Stop 29  1/320

As in the short distance subject, the 'noise' can be dealt with.  Another characteristic I'm looking for is the detail in the ice formations.  At ISO 1600, it is OK.  

So for HDR purposes, I wouldn't be afraid to push the ISO to 800 or 1600 if I needed the aperture settings or speed.