I've had my main topping lift for over ten years, with a lot of sailing, as a charter boat, sun and weather, being in the tropics. Polyester double braid is what we use. I doubt I'd replace it with anything else.

 

Yep, good 'ol double braid. Cheap too 😊

I am just replacing mine... Fortunately it doesn't terminate at the masthead but goes down in the mast. I am upgrading it from 8mm to 10 or 12mm to be an emergency main halyard. Nice for long range cruising 😊

 

What a fantastic idea! Just hang a block instead of a thimble.

 

I have used the predecessor to Viper- New England Rope's VPR for close to 15 years. I liked that product a lot. Viper is New England's replacement and I have used it on a number of applications, including halyards on a boat that I have been racing on. I like it better than the VPR and the core is supposed to be more durable. Depending on the diameter, Viper will be one or two mm smaller than polyester and will have less stretch and a similar strength. It seems like the Viper is close to the same price as similar strength polyester (which will be a bit larger diameter) . That said, I was recently advising a friend on this and the size he needed was $.30 per foot more for the next smaller size Viper, whereas when doing the halyard for the race boat, the Viper was actually less expensive,

If you think that you will use this as a temporary backstay, then I would definitely use the Viper. Viper should also be a good choice for a spinnaker halyard.

I think that Marlow Rope is more common over in Europe. I am not familiar with their line and they do not publish elongation numbers which I consider important for halyards since stretch adds to fatigue, and to chafe as the line moves back and forth across sheaves and exit slots.

Jeff