Double braid polyester of the appropriate diameter is likely the type of line provided by the builder
when the boat was new and is generally considered to be adequate.
The principle benefit to the using Spectra is that due to the comparatively greater strength, a significantly smaller diameter single
braid line may be used which in turn reduces the amount of weight aloft. Reducing weight aloft has an impact on reducing inertia which reduces hobby-horsing as well as providing a benefit in terms of stability.
Generally speaking, the use of Spectra halyards tends to be limited to the go-fast racing
crowd but I believe many cruising sailors would benefit it as well, in particular those who like to actually sail their boats. Whether or not the cost is justifiable is up to the individual to determine.
With regards to cost, I don't have a catalog in front of me but in general, owing to its superior abrasion resistance and strength, when you switch to high-tech lines you can go down in size as well as make the switch from double to single
boats will sew on a cover over critical areas such as where the halyard
goes over the masthead shelves, sometimes the turning block at the deck
, and very often at the halyard winch
to provide chafe protection.
High tech line for sheets
? Maybe not so much. A lot of times sheets are oversized to make them comfortable to pull on with your hands. But not always. Generally double braid polyester is the way to go. High tech line is great for things like light-air spinnaker
sheets, but small diameter high tech line is tough on your hands.
The down side to high tech line is that it can be difficult to cut, but it is very easy to splice. Personally, I use it for my lifelines
where I think the benefits are both in cost and performance. It can be cheaper to replace with high tech line since you don't have to buy any stainless turnbuckles or fittings.
Just splice an eye in one end and loop it around the pullpit, splice an eye in the other end and use lashing to develop some tension when attaching to the pushpit at the other end. Very simple, the lashing might seem old fashioned but it's what all the fancy expensive racing yachts do.
PS without knowing but guessing based on cost it would seem they are trying to sell you a double braid spectra - that is to say a spectra core
with a polyester cover. Use single braid spectra for you halyards, it's a lot cheaper. You can make a cover by stripping one off of some old junk line. Don't use the double braid spectra for your sheets, stick with polyester for those.