The tube material definitely shags out and gets more stretchy. In addition to the stretchy old canopy material. The front tubes bend and twist. So the wing tips cannot be properly supported which means excessive leech twist. Once the Dacron loses the resin treatment, it has no stiffness along the 45 deg orientation with no fiber to help. Also the front tube bends in the middle so the tips flex inward and the canopy shape gets deeper in the gusts. I think the torsional twisting of the front tube is a bigger problem, but both issues are killer slow for upwind perf.
I've rebuilt the canopies on three 2021 Slick wings using DP's CodeZero material. It took me a while to get the shape how I wanted them. Once the shape was nice, it's obvious how the front tube flex and twist impacts the flying shape under load. Ended up with three full length light battens (middle and each side). 3.5m in a pic below. The battens are excellent for draft stability and the full length middle batten (adj tension) also works like a camber inducer for much more effective pumping. I also implemented a middle draft rope + micro pulley control system for changing depth on the fly, like an outhaul adjuster. Yet to add a cleat, but sure it'll work great.
Learning a practical and low cost solution to retain or restore the stiffness of the tube material will be a game changer for longevity and higher performance. A bonus would be the water repelling features. That Aero Shield product might be really good - anyone tried it? Or has anyone painted a water-based acrylic primer paint on the front tube? I have been considering removing the bladders and heat bonding some carbon fiber tape to the tubes. Pretty sure that'll work. I could additionally do the thin primer/sealer paint or the aero-shield.
DP's CodeZero material is excellent for the canopy. Although it is much more difficult to get a good fit compared to stretchy spinnaker cloth that hides errors during manufacture. Comparing lightly used vs used, when wet, CodeZero is I suspect lighter than the nylon spinnaker cloth, because the tired spin cloth holds a lot of water. I takes some time to build a pattern with desired shape and aligning the aramid fiber with the typical sail-wing load lines.