So I couldn’t resist and bought a copy of Photomatix and I can at least generate images without a watermark! The coupon code from Stuck in Customs helped. I’ve been having some fun and will need only several years and a lot of luck to get an image as good as those from Trey Ratcliff. Here are a couple of my attempts, comments always welcome.
I quite like the shadows and angles in the one above.
Both these images are of the Christchurch Art Gallery.
Photomatix is straightforward to use but obviously working out which sliders to use to get the effect I want will take some experimentation. The HDR tutorial on Stuck in Customs is a great place to start though.