I've made the case here several times that using high tech line in multi-part purchase is a waste of money and may be less satisfactory than standard Sta-Set double braid. Fully trimmed, you have at least four and typically six parts bearing the mainsheet load over a short span. I could go through the sheet load, line tensile strength, and stretch calculations, but it is simpler to consider what you have in your hand. In 20 knots of wind, you can probably still trim the mainsheet with one hand, so the load on each part is likely less than 100 lbs. Smaller diameter, smooth finish line runs more freely, while larger diameter soft cover line is easier to handle and holds better in the ratchet. If you are still set on spending extra, be careful not to get a line that is stiff or will stiffen up from exposure to UV since the mainsheet spends most of it's life in the sun.
