I think these types of girth are a bit like marmite. You either love them and have no issues or you don’t like them, have issues.
I tried the Busse dressage synthetic string girth. If anyone has a Stubben one, and can tell if Busse is a cheaper version, please email or leave a comment.
My riding instructor doesn’t like them. My horse started out fine but changed her mind. I rode in the synthetic version for all of one month and found jumping it allowed the saddle to move where my other one doesn’t.
It didn’t keep my saddle as secure as my previous girth for hacking. I found it allowed it to move ever so slightly. On a wide type that’s not ideal.