I built a MC16.5 from plans last year and I've had a lot of fun with it since. This year I'm planning to build the outrigger sailrig. I'm thinking of stitching the amas with 125 lb breaking strain nylon monofilament instead of copper wire. It's a bit thicker than the wire (1.2 mm) but still strong enough to cut through the okoume plywood if you over tighten it. Obviously you can't just twist the ends together, you have to tie them with a suitable knot, put a short length of dowel through the loop and twist. If you do two at a time you can then lock the tommy bars together to hold the tension.
As I see it the advantages are:
Cheaper than copper
Nylon doesn't work-harden, so you can tighten and release stitches as many times as you need to while straightening the hull prior to filleting
Nylon becomes invisible when embedded in epoxy
It's a bit more fiddly than just twisting with pliers
Anybody like to comment?