Yeah Taught steel cables snapping are a hazard. Not sure how much better copper is, but for some reason I imagine getting smacked with a copper braid over a kevlar wire is going to be much better then getting smacked with a stainless wire rope. Always keep people nearby in mind too, not just the setup guy. Big wires will decapitate you if they snap I heard.. but that is cranes, but it would not take much I think to cut open the neck. Part of the reason why I am doing research too. And as always, eye injuries are no joke, even from thin wires
There is probobly a diameter under which there is little threat for wire rope, but I don't know what it is.
I am kinda thinking for temporary installations a fiber rope of some kind of going to be much more acceptable, especially if its taught.
Also something that randomly came to mind is hanging a pulley on the pole with a weight to keep it taught. Maybe the strain on the wire would be more consistent that way, but I know nothing of the practice, and of course ice would fuck that up big time, it would need a brake of some kind when it goes into 'overload' tension from ice or wind.
Trees are even more chaotic because branches can break.