Wire, spectra cord, it doesn't matter. All the instep strap replacements will wear out over time. Usually the gaiter explodes during use at the more inopportune moments.
I like the results of my experiments drilling holes through the midsole, but the straps still fail via abrasion when in rough terrain.
So now, I use stretch gaiters, usually OR Flex Tex (most durable of the lot that I've found) and stitch them directly to the upper of the shoe, leaving the velcro front and front tab free to do their thing.