My Mistress and I have a metal sounding set but we’ve never used it. I think there is a fear of injury on her part. Me being the dumb male, I’m less concerned and would be willing to try it. I do think it is quite the mindfuck to see metal going in and out of the penis. Cumming from that would be humiliating to me. But I do like the CBT and torture aspects of the activity. Of course I’ve fantasized about having cock and scrotum nailed to boards before - so sounding is a step down from that.