Firstly, let me apologise to Don for hijacking his thread, these things are sometimes like chinese whispers and the subject seems to end up totally different to how it started out
Pol, I seem to be having a problem with the way in which CS2 is blending your images in the example you have shown. The sky in the blended preview still seems burnt out in places, whilst the the shot taken at 0.0EV seems to look pretty good in the sky area. In fact the preview looks much like the one in the +2.0EV. So whats going on here? Could it be modified by switching off one of the images at the extremes for example. The sky area in the example you posted earlier in the thread seems much better to me, was that produced in the same way or is that the result of applying tonemapping to the resulting HDR image. If so I would argue that some of the tone we see in that other example is the grey infill that the plugin seems to apply to blown highlights.