I think the sunset must have been amazing - would love to have seen it myself.
As far as the composition goes, I think this would have been much better in a horizontal orientation. The mountain to the right is cropped right through the middle and my eye is drawn immediately to that. You've done a great job with Photomatix as you have managed not to increase the noise levels too much (always hard with low contrast scenes) and have avoided the "cartoon" look. The reds are amazing - not sure how pumped they were in editing, but either way I feel like I can imagine the sunset.
A couple of other reasons you may have scored a bit lower than perhaps you would have hoped: in a sunset/sunrise challenge some people may actually be looking to see the sun itself in the frame. Also, in a challenge with such strong competition I think this probably lacks the WOW factor, but largely, I think the main reason is the orientation of the photo.
The intensity of the red on this almost makes focusing on it difficult for my eyes. I like the background, but wonder if you might've been better off focusing on the left prominance and changing your perspective so that the canyon and right prominence weren't intruding in the frame. Of course, I have no clue what's to the left, so maybe there's a giant high tension power line screwing up that whole suggestion.
when I scroll down to see the whole picture...I like it better with the little valley out of it...makes the colors stand out more with the formations (mountians?) and the clouds only....