My friends have used them before. They actually hold up quite well. Will last over a year if done right.
if done right. that means a solid mount. movement will fatigue lesser wire as mentioned earlier. That being said, I've fixed exhausts with coat hangers, twine, soup cans and bungee straps.
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It's "Dr. _paralyzed_" actually. Not like with a PhD, but Doctor like in Dr. Pepper.