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The precision of the beautifully indexed down tube shifting of the 9 speed campy eliminates all the dangers and problems of trying to line up gears whilst in the 'suicide' position at speeds. The 'unnecessary complication of a design' as you put it is what I consider the pinnacle of down tube shifting. I'd never return to friction after using indexed gears. I'm not a fan of regression!
Indexing on DTS is an unnecessary complication of a design, who's beauty lies in the simplicity (although retrofriction were the acme).
I almost feel nostalgic for Simplex SLJ...