I bought Photomatix last autumn to try some HDR landscape stuff. As you have done, I found that the preview bears little resemblance to the final image. I found the final image to be oversaturated when compared to the preview. It made using the software a real pain because I was always having to try and allow for this change when adjusting the sliders. I also quickly came to the conclusion that even a well manipulated image looks too artificial for my taste. I haven't used the software for months now.