The Compass straddle cable is intended only for our brakes, as well as old Mafac brakes that use a similar system. Using the thinner straddle cable with other brakes can be dangerous, if the cable is clamped in a groove that is intended for a thicker straddle cable. Under hard braking, the cable can slip, making your brake ineffective. Furthermore, an attachment that clamps the cable puts stresses on the cable, and a thicker cable is better able to resist those stresses.
The thinner straddle cable of the Compass brakes is part of the entire system (swiveling mounts, eyebolt to hold the cable securely), and should only be used as part of that system.