Resonant steel sounds way better than zinc alloy, and these thin saddles are lighter. I polish the top, where the string touches it, like you have to polish frets. Supernice tone.
Edit: after some experiments, I noticed you have to narrow down the saddles so they don't touch each other. They are 10.8mm wide, they need to be sanded down to 9.9mm or 10mm. That's because if they touch each other, when you hit a string the energy is spread into the five other strings, so the note you play is weaker and a bit dull.
Obviously, the energy of a single pick strike on one string is not enough to vibrate six strings. So now I separate the saddles - it takes about an hour to sand them down to the proper width - and notes are better articulated, clearer and more powerful. Sympathic resonance is still there, but with no muddiness.
When you play a chord each note rings cleaner, and the whole chord is more shimmering. It's easy to see if you have a bass because the saddles have lateral play (at least with traditional Fender-type bridges), just push them aside. Strike a note, it's clear. Now reunite the saddles so they touch each other, hit a string, it will sound a little dull and weaker.
I have installed the Göldo saddles on six guitars, three have the narrowed-down saddles, three have the regular width. Those with a gap between the saddles ring with more clarity, the others have some mudiness; I will do the same job on them; it's tedious to rub metal on sand paper (60-grit because that's hard steel), but it's worth it, and the improvement will last forever.