GIMP is not there yet, it's only 8 bit per channel http://www.gimp.org/docs/userfaq.html#c16bit
Corel PaintShop Pro $70 http://www.corel.com/corel/product/index.jsp?pid=prod4900069#tab3
I like GIMP with ufraw. I know people find it's interface to be pretty crap, but I actually find its quicker than Photoshop once you learn it.
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