IMHO, properly setup, Did-Compe safety levers should function well enough to stop the bike in most instances. I have some on a casual rider I ride on a local bike path and they are handy enough. I had cheaper, no-name versions on bikes as a kid and they were as useful as a fart in a whirlwind.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke