Pixelmasher: I believe what Keen is (correctly, it seems) saying is that you won't get 'fairly sharp' edges at all. You'll get entirely sharp edges, making the normalmap and specular much less useful, in my opinion. If that's what Medestruit was going for: fair enough. Nothing in life is that sharp, though, and rounding…
Seams from islands is only used as a lead-up to selecting the mark as sharp feature... You could always select the entire mesh and clear seams once the edges are marked as sharp :P