The sources are rather dated and not entirely applicable to today's sails, construction techniques or options. The best advice of all of it was by Island Planet Sails, an actual sail maker, which you seemingly chose not to listen to. That's why I suggested people often search the net for views that support what they want them to...
We're still a long way from a 50/50 split....


I personally don't know any sailors, and I know lots and lots of them, not just racers but cruisers too, who would swap a batten/roach main for a battenless / roachless one.
I have a customers boat which I decommissioned in the fall. The full batten main was built in 1986 and is still in "workable" condition..... The stitching has been redone about 3X and the fabric is real soft and she's not the best performing sail at this point but the battens are the least of the worries on what was even then, in 1986, a "cheap" sail, and is today still going... My guess is that this sail would still out perform a battenless & roachless brand new sail..
I have a few "retired" sails in the barn and none of them were retired for anything to do with the battens. The battens and pockets all outlasted the sail...
In over 40 years of sailing family boats and my own I have never once had a sail that suffered short life due to battens. I lost one batten, back in the late 90's, but that was my fault and it cost me all of $13.00 and about 10 minutes to properly fit it. I've misplaced battens during the winter and mixed up battens for old sails with newer ones but that has been the biggest draw back to what have other wise been huge performance boosts over the alternative of no battens and no added roach.
Since fiberglass battens hit the scene I have never broken one. I've had many sails re-stiched and a few older style batten pockets too but all of these re-stitches were caused by UV not by the battens The sails needed it even where the battens were not.
I've owned standard batten sails, full batten and top two full sails. I have also owned a boat with a battenless & roachless furling main so I can actually speak from actual experience with all the batten or battenless options.
That battenless sail was by a long shot the worst performing sail I have owned, though I did have an antique cotton duck sail back when I was kid that was pretty bad too...

The furling was convenient, loved it for that. The sail was really poor performing though... Loved the "ease of use" with the furling main but HATED the performance hit..
Your talking $465.00 for a standard C-22 sail or $520.00 for a top two full battens C-22 sail from National Sail. If I owned a C-22 I'd be opting for the top two full option, but that's just me.
Can you please list your primary reasons for wanting to go battenless/roachless? Perhaps we can help you make a decision that will help you sail your boat better and enjoy it more....
I would urge you to consider the performance (as in sailing performance not "longevity") hit you'll take....
P.S. I guess your buddy is not familiar with PubMed, clinicaltrials.gov etc.?? Same stuff he gets in his peer reviewed journals but you don't need to dig through piles of old journals to find the clinical trial data you want...
The dark gray area is what you give up by having no roach, no battens. Actually more correctly stated, you give up more than the gray area because they cut the roach slightly "negative" so they are less prone to leech flap & flutter.