Not really rigid
The rigid vang in your photo is really a spring inside a tube, and uses a block and tackle setup to tighten it. It will hold up the boom, but I wouldn't recommend it. I have a rigid vang setup on my Beneteau 323, and still use the topping lift to take the load of the boom off the vang when docked. The rigid boom setup restricts the amount the boom can rise, and that could be either a good thing or a bad thing depending on circumstances. If you get into a broach, and blow the vang, the boom isn't going to release very far.