"Send for a Leech!" yelled the doctor...
Some dimly remembered perspective:
In the early 80's I recall crewing on a boat with the "newest thing", full battens. This did several things that benefited the boat and also the sailmaker.
The added roach area was quite large compared to a traditional main. The added area and the whole main also had good shape due to the battens. On the downside we had to force that leach around the backstay where it hung up on every single tack or jibe in lighter airs.
It was also different in flaking on the boom -- you just pulled the battens into order on top and the cloth pretty much had to follow. There was some downside in that the weight aloft went up.
On the whole it seemed like a good idea compared to traditional batten schemes.
For everyday sailing, it was marvelous (!) to no longer have all that shaking and sail cloth noise (and damage) while luffing up.
Hoisting, reefing, and lowering got a LOT quieter.
This was before the plastic "strong track" came into vogue as I recall.
For the sailmaker it was a solid win. The extra cost of added cloth and added batten sewing was more than offset by the trendiness that attracted the buyers. Sailmakers could use cheaper cloth since the battens supported the designed "shape" -- this was like the hugely successful Hobie Cats with their full batten mains in the 70's. The Hobie could use cheaper material and still have decent sail shape; and given the high loads from driving on one hull as the apparent wind always went forward to a high-pressure close-hulled trim often, made the sails last well too.
By the time we get to, roughly, the 90's, sailmakers were pulling back from the earlier extreme of all-full-battens. Customers were vexed by the friction on the slugs, even using the longer slugs at the batten points. Hardware designers came out with specialized slug replacements for big $$, and finally the plastic insertable track system from Strong, combined with purpose-designed slugs made the hoisting a LOT easier. (even bigger $$$$)
Sailmakers then started leading their customers back towards the "2 + 2" batten design, which gives the sail about 70% of the benefits of the all-full-length idea with a lot less hoisting and dropping friction hassles.
As an example, we have never needed to install a Strong track system on our boat with our 2 + 2 batten system. I do spray all the slugs with 'MacLube' once or twice a season.
Our sail is quiet when luffing.
Cost is reasonable too, compared to a design having all panels shaped into load path patterns or having the whole sail "molded" out.
Having said all that, I would probably buy a Tape Drive main if replacing this one, just 'cause I like the looks! (Logic and boat ownership are concepts often foreign to each other...)
Pontificating performed while U wait.
Cheers,
Loren