First post, just joined on a recommendation and hope you find the thread of interest!!
Geostrut is a carbon Fibre mast system that is a pretty direct competitor for steel. Structurally it is stronger, but it weighs in at about 10% of the weight of steel. Manufacturing technology advances means the costs are similar, but you save a significant amount on all aspects of delivery plant, installation time, Labour and through life maintainence costs
Be very keen to share some further details if anyone is interested to talk it through.