Have you tried textured or geometric polys? I've had good luck with SP Tornado, a heptagonal textured poly that holds tension really well, especially when you mimic the Fed setup (nattie main/poly cross). Expensive with the nattie but worth it if you don't shred it quickly.
"When a man is tired of London, he is tired of life"...Samuel Johnson 1777
"When a man is tired of Federer, he is tired of tennis"...stringertom 2014