We have a dyneema/amsteel backstay on our fractional rig... we have a roachy main and use a whip to ensure the sail clears the backstay on light air gybes and tacks. (Wire would have been too heavy)
Some tech info here:
AmSteel Synthetic Rope Technical Information
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)