This seems to be more of a brake, rather than a true preventer, so I'm not sure how to answer your question as to whether this would be better than a vang.
I like the simplicity of this product. However, it may be that you'd still need to use a typical vang/preventer, and that this apparatus would simply help to effect a controlled jibe after the preventer is released.
But maybe it can be snugged tight enough to act as a preventer also?
I too am a fan of Wichard products. Thanks for the link.