After I posed my question, I did some Googling and found this:
Image deconvolution iterations reach a plateau and then only seem to enhance noise. In my experience it is best to find that plateau and stop the iterations just as the plateau is reached. Then run unsharp mask or smart sharpen on that result and try additional image deconvolution iterations using a smaller point spread function. A final unsharp mask on that result can help perceived sharpness. The multiple combinations of image deconvolution and unsharp mask (edge contrast enhancement) produces the best results in my experience with hundreds of images.
Hey, its on the internet so it must be true, right?
Seriously though, it looks like something worth investigating when I have spare time. I guess I can export the file from RT and then reopen it?