Is there a good reason for not using Dyneema for shrouds on a gaff cutter?

[Andrew Craig-Bennett]

It just struck me that I might replace 10mm wire, parcelled and served, with soft eyes at both ends (round hounds and round deadeyes) with 12mm Dyneema (black, obviously!)and thereby save a great deal of weight aloft.

There must be a reason why members of the super-competitive crowd who race Colchester smacks and Falmouth working boats are not doing this - can someone tell me what it is?