Thanks for the file, Craig.
I typically take the part from the link that seems useable. I have no idea what happens while you paste the link into the post, The < a > stuff is presumably not your doing. Anyway, I know what to do, so we can continue in that way, no problem here.
I was not certain why the Noise shader is the key. If a random appearance is needed, then this would be a way to go. No Concerns here!
I have added a Plain Effector with color only and one which uses the “Visibility” option—“Plain.Vis” is the suffix I gave it, to make it clear. These internal visibilities work only digital, on or off (<50% or >51%)
As long as you use Color and the MoGraph Color Shader, have an eye on the Cloner Effector, it is most of the time best practice to set the Paramaeter> Color to black. In this way the Cloner Effector has no influence on itself.
Another method, not in the file, is given with WEIGHT. The first Effector defines what can be visible and what not, and everything in between, but this Effector is not responsible for the final effect.
The second (below in the list) Effector is using this Weight information (his is set to zero) and in that way this Effector cares only about visibility. Where is that preferred? Think of the first one as noise that moves over a field of clones, but the second one makes only a group visible, inside of that visibility field, the noise shows results. So you can move and change the value of each based on the noise independent from the area of visibility.
If there is an interest in this, I’m happy to set up a scene file.
The scene file below has three way, I changed a lot in it.
Let me know if there is a question. :o) I’m happy to explore this.
All the best