In Photoshop, I set the radius to 9.5.. and this before resizing. Which, in turn, probably added a lil' bit more sharpening (although, I did select Bicubic Normal for the resizing).
So.. you could probably be a bit more aggressive with the setting/sharpening. The image quality is that good good.
Here's the method I used (save that of the desaturating step) and for Photoshop: