Anyone Else Use an Angle Adjustable Mountain Bike Stem?

[radderfire]

Hi Guys

I've just fitted an angle adjustable stem to my mountain bike, it's made by System EX. It's good, but one concern is that the angle is held in place by a single allen key bolt, and I wonder if this could ever fail badly. I would not want the handlebars to flop down when I am flying down hill. Has anybody else got one and have you ever had any issues? Am I worried about nothing?

Thanks

 

[radderfire]

I'm guessing the designers have thought about safety when designing the product, I was just wondering how they might have achieved this.