Synthetic line has lots of advantages over steel cable. In the maritime industry, most ships have done away with cable in favor of synthetic line. The synthetic stuff doesn't store kinetic energy, so it's safer when it parts- no snap back. Steel cable can kill you if it parts. Synthetic line isn't as fragile as what you guys seem to think. We have lines on this ship that we've left out in the sun and have been exposed to high temps, freezing temps and salt water (obviously) and they still work fine...would be best if we stowed them properly but they don't seem too concerned with that aboard this ship-that's another story. A good quality synth line doesn't need much in the way of care, a winch cover when not in use would be good, and use of chafing gear (abrasion sleeves). I would go for a high quality synthetic line. Also, synth line is more forgiving in the drum when it's bird-nested (which is when it snags and fouls up on the drum while winching in). When wire fouls, it bends and and flattens and the strands become weak and can become permanently kinked to an extent. This makes the cable weaker. This is why it's important to carefully winch in wire cable. The synth line is more forgiving when it comes to that, since it has elasticity and will return to normal shape when it's pinched (unlike the steel cable).
So in my opinion, high quality synth line is a good option.
