The coolest disc on my machines are on the outlaw and bandido II Micromax.
They are ed-120ish close to your silver
I can disc a dime and hit a quarter and copper. I can pick up a copper and block quarter and dime.
I think it's a ed120 thing because at minimum it blocks iron, meaning that the same turns on the disc knob spread out what's left above iron. Think of a piece of rubber. The ed120 is a smaller piece of rubber representing above iron all the way up to high conductors, it's just stretched over the same "arch" and the ed180 larger piece of rubber. The ed180 machines will usually compress the higher conductors at the top to make room for the lower conductors and iron at the bottom and will only disc high enough to just below the dime area. I.E. at Max you hit dimes, copper and quarters and silver.
Because ed120 has no area down in iron because it's disced out at minimum, the top end has more spread area and can go higher so you can separate dimes, nickels and copper/silver and depending on the model can even separate out copper from silver.
Hope that makes sense. Made sense when I wrote it, but hopefully the point got across.