Some kiter (me included) used the safety leash with the flat kites (such as the Waroo) only in overpowered condition.
The chicken loop on a bar apparently can be released in extreme conditions (this could be a feature of the bar safety release system). It happened to me at the end of the day roughly the time when the wind averaged at 35.6 and peaked at 49.1 NSC knots (I was on the school 5m Waroo, not overpowered and forgot to clip on the safety leash). The chicken loop accidentaly released (why?) when I came in, fortunately after the bar got ripped right out of my hand, the kite just dripped and landed safely in the wind shadow behind the rock pier (also fortunately it was late in the day so not many people around).
From now on, I would recommend all kiters to wear the safety leash with the flat kites in all conditions as the chicken loop (on any bar) can be released suddenly.
So wear your safety leash all the time regardless of flat kites or C kites.