I've been experimenting around with Photomatix. Found out that trying to use several exposures of a scene with anything moving in it does not work very well. Lots of ghositng in the trees. My work around was to take a single RAW file and in the RAW converter adjust the exposure from
-2,-1,0,+1,+2. I started with a photo that was somewhat neutral, exposed slightly more for the shadows. I did that to try and reduce noise. I saved them as jpegs. I then loaded and processed these in Photomatix and tone-mapped with the detail enhacer for a somewaht natural look. Even doing it this way the waterfall still did not look right.

My solution was to do a traditional exposure blend using the HDR photo and then a photo from the same RAW file with the exposure adjusted for the waterfall. Made a mask of the waterfall and used that to replace the HDR waterfall with the photo I adjusted just for the waterfall.