How to improve your photo
Experiment with leaving more space around your main subject. Try different crops in post-processing. No one crop is the definitive one really, but you can say different things with different framing. Try creating environmental portraits where the objects or landscape surrounding the main subject tell us about its life and history. You are a story-teller Douglas, so tell your viewer as much of the story as you can.
Consider tweaking the sky less severely. I know this is a subjective area in HDR photography but I do feel that a lighter sky would work better. This is a subtle thing and a personal choice, not really a criticism, and overall I really like the shot.
As you are using a tripod, you can choose to use the smallest ISO possible so that digital noise is reduced to a minimum. Also, if you want to use long exposures make sure your camera has the Long Exposure Noise Reduction feature enabled. This is separate from the ISO Noise Reduction feature and can be left on all the time.
A very long exposure would have perhaps given some soft motion blur in the foreground which would have acted as a nice counterpoint to the stillness of the barn. Just an idea, and worth experimenting with perhaps.