Thought I'd post the bug reply here in case anyone has any ideas:
Playmaker gizmos are drawn in OnDrawGizmos using Gizmos.DrawIcon.
In other words, they use the standard gizmo system. I'll do some digging, but I'm not aware of any way to control the draw order of gizmos, or to even know about the other gizmos being drawn...
One thing you can do is collapse the PlayMakerFSM inspector, which will hide the PlayMaker gizmo for that component.
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I actually never noticed that collapsing a component in the Unity inspector collapses all instances of that component, so it actually hides all Playmaker Gizmos.
So I'm not sure what the best solution is...
Anyone have any experience with Gizmos.DrawIcon? Any ideas?