Yes I had it done. 23 Jan, 2024, a redo adjustment of an inserted valve, one of five left lung, upper lobe on 9 April, 2024 and finally removal of all Zephyr valves, 30 May. 2024.
No it did not help and there are no guarantees. It is a bronchoscopic procedure under general anesthesia: Intubation, camera and valve and instruments go through the tube they put down your throat to get to the particular lobe selected after testing determines the selection.
Damage to vocal chords does occur and is common with intubation and happened in my case. Months to recover my voice and now in Speech therapy.