The toughness of sharpening really depends on how radical the recurve is. If it is a short blade with pronounced inner curves then sharpenning it can be tough without nice stones (etc.) that will fit mostly flattly against that inside curve. The Spyderco Sharpmaker is supposed to be a great design for sharpening even the most radical.

Does anyone else's Scrapper 5s have slight recurves to the blade? Both my Cg and Le versions hate it, but very slightly.