As would any conversion job be. Or programming. Or any other task that's basically number crunching.
C&C is a fine game. It's great that experienced users can convert on the fly, once they've done it a few times. I keep hearing about the ease of conversion, and then I look at my own C&C books and shake my head. It's not there, folks, not for d20-based material. It's just as much work as any kind of conversion is, and becomes less so once you're experienced.
IMO, the vaunted compatibility is a myth - there's not much to the C&C system, therefore it's easy to bolt things on with effectively GM fiat. Is it quick? Sure. Is it hand waving, effectively? IMO, yes.
Where C&C does shine is (as others have pointed out) converting the bizarre and often nnonsensical pre-d20 material to a clean, (semi) consistent system. Where it falls short for me is that it's not enough of a system, and hearkens back to the days when GM fiat effectively ruled the table.
YMMV.