I received the brake yesterday. Unfortunately, it's a no go on my XDM. The barrel apparently needs some type of shoulder on it for the outer aluminum piece to snug up against. The outer piece just spins and slides on my barrel after the inner piece is tight. I don't know about the CZ threaded barrel.
I ordered mine directly from Rex Silentium. I sent them an email first thing this morning asking if I was missing something in the installation (it couldn't be anymore straightforward). They responded super quick and let me know that they agreed it wasn't going to work and would refund my purchase. Going to put in the mail back to them tomorrow. Looked good on the gun, wish it would have worked. I appreciate their super quick response though.