I thought that entire concept went out with the old Simplex and Cyclo bandspring rear derailleurs. I admittedly haven't snapped a shift cable in years, but I would worry that slippage or breakage of the control cable could throw the chain into the spokes. I'll stick with normal high on the rear derailleur, thank you. (In the early 1970s, I did use SunTour's reverse-shift normal high front derailleurs, which worked fine for half-step gearing, but less well for large drops and/or triple chainrings.)