I do think there are probably some "improvement" to be had by switching to XTol, DD-X, D-76, or Perceptol BUT it isn't even close to what a film change would get you AND finer grain means less sharpness, you can have one or the other. Only you can decide which is more important.

So, onward to considering the example shot you provided, why not just step closer to your subject?

Cut the distance by half or 2/3 (with the same focal length) and you have instantly reduced the size of the grain in relation to your subject matter by half or 2/3.