Yes, tonemapping is a very powerful tool. Photomatix has a particularly nice local tonemapping operator. This is a really cool image. Thanks for posting. One thing to be aware of though... the photomatix tonemapper has been pushed to some extreme levels by many users, so that super dynamic contrast, deep blues, and enhanced edges is starting to become the unfortunate definition of "hdr" images... That is NOT a comment on this image, which I think has been tonemapped appropriately, and looks great. Just be careful with pushing photomatix too far;) it's becoming the "lens flare" of today;)
That said, even gamma adjustments can bring out a lot of detail in a flat (subdued) exr, which is the most basic form of tonemapping. I generally render pretty bland images so I don't blow anything out, then use gamma, gain, etc in fusion to adjust the image in post as you did with photomatix.
Good stuff. Any info on the cloud setup would be nice to know;)
Andrew