First HDR attempt - Natural Arch

On a trip to SE Qld last weekend for a mountain biking race at Kooralbyn I had a couple of hours spare and decided to re-visit Natural Arch. I last went there over 20 years ago, before all access restrictions were in place, but the dynamic range of the scene on a sunny day was way too much for slide film.
I figured this would be a perfect test for Photomatix, which I had downloaded a couple of months ago, but not yet tried.
D200 + Sigma 30mm @f/8 and 4 exposures ranging from 1/8 to 1sec. Photos taken with a cloudy sky WB, but I have added a bit more yellow as the sky reflection on some rocks was rather blue.
comments and suggestions welcome
I figured this would be a perfect test for Photomatix, which I had downloaded a couple of months ago, but not yet tried.

D200 + Sigma 30mm @f/8 and 4 exposures ranging from 1/8 to 1sec. Photos taken with a cloudy sky WB, but I have added a bit more yellow as the sky reflection on some rocks was rather blue.
comments and suggestions welcome