WebBikeWorld.com tests some aftermarket horns. Interesting that both Stebel Nautilus horns they tested (different models from different retailers) were faulty, these are the much-hyped horns used in the Genuine Buddy “International” models.
The authors point out:
By way of disclosure I’ll admit that I have fortunately never had to use a motorcycle horn in anger. […] I consider a horn to be a safety device of last resort — if you have to use it, you’re already in a situation that probably could have and should been prevented.
Good point. a loud horn is useful as a proactive warning to make sure a driver notices you before a scary situation arises. Once you’re in a scary situation, there’s no point in honking, you should be concentrating on braking or swerving.
(Thanks for the link, Davek, here’s his thread at Modern Buddy!)