Rod has a couple advantages not always mentioned. A slip neighbor about dropped his rig last summer when his roller furler top fitting grabbed the wire headstay and unlaid it, breaking all but 2 or 3 strands. Less likely with rod. Rod is slippery. We have a rod backstay and the mainsail roach overlap slides by in light air easier than wire, and you''ll see less chafe. Cruising take a length of wire that will work for the longest stay with Sta-lok fittings that fit your rig. No rule against wire mixed with rod, especially in emergencies, just watch the tension as they stretch differently.