This year I decided to try a less expensive and possibly just as good alternative to the usual fly line backings like Dacron and gel-spun lines.  Dyneema seems like the perfect alternative.  It doesn't stretch, is really tough and thin for the rated breaking strength.  For the rated strength Dyneema actually appears to be thinner than gel-spun backing at less than 1/2 the price.  So far it has worked great, but I haven't caught anything big enough to test the backing strength which means I haven't been salt water fly fishing yet this year.

Anyone else trying this out and have helpful feedback?