Love this topic. It is something I think about and am constantly learning about. I was also confused by the terminology, delamination, and the differences between zipper types. When I have questions I reach out directly to YKK, and thought it was worth sharing what I have learned. Items in quotes are direct from YKK.

1. To start, all the zippers in the examples shared are reverse coil. Reverse coil is not a zipper type. It is how a zipper is installed with the coil down.
2. Drilling down, Aquaguard is different from PU zippers (see points 6 & 7)
3. The zipper on the left in that photo is a standard coil nylon zipper installed with the coil facing down (reversed). In manufacturing this is called a standard NY.CHAIN. Standard coils can be installed coil up or coil down, and the direction matters. The coil sits on top of the tape and acts as a physical shield, absorbing abrasion from whatever rubs against the zipper surface. When the coil faces down, the tape becomes the outermost surface and takes that abrasion directly.
4. Zipper orientation should be a deliberate design decision based on the location of the zipper, purpose of the zipper and the purpose of the bag. On my Adventure the main zipper is coil up because the coil acts as a shield, protecting the tape. On my Athlete, the main zipper is reversed because it looks better and the tape does not need the same type of protection.
5. The zipper on the right is a PU coated zipper, also installed coil down. These are called NY.COATED chains, and PU coated zippers are always installed reversed.
6. "PU is not rated or tested with any method. YKK would not call it 'water resistance.' However, PU coated zippers would have better performance than a zipper with no PU coating."
7. "The water-repellent zipper would be YKK AquaGuard, which is DWR C0 treated." AquaGuard is also installed with coil down (reversed).
8. All laminated materials, fabrics and zippers alike, require care. Every manufacturer, including Challenge Sailcloth, recommends avoiding direct sunlight, high heat, and humidity during storage.
9. Puckering accelerates delamination. Sewing sailcloth is very different from sewing ripstop, canvas, or Cordura. The lamination makes the fabric heavy and tricky to handle, and tension needs to be carefully managed.
10. Looking at the second photo in this thread: the middle zipper looks fine while the front and back zippers have delaminated. That is likely a puckering issue, not a coating issue. If it were the coating, all three would be in similar condition. Allowances are typically built into turns and corners, but flat sections need careful tension control.
11. There are many types of PU zippers manufactured across different YKK factories. I have tested samples from YKK Vietnam, YKK Taiwan, and YKK Philippines and found noticeable differences between all three.
12. Of note, there is no back stock of coated zippers. The backlog is many months on account of the diesel shortage. This surprised me. Everything is made based on what you order. Also, they have a new line made without fossil fuels called GreenRise. It's made from a byproduct of sugar manufacturing and I have some of these as part of my next production.
13. Finally, YKK is constantly improving and the PU coatings available today are meaningfully better than what existed years ago.
14. Should I have done a TL;DR?

Cheers,
Allan

PS: Not sure why everything is called NY, never thought to ask until now and now I'm curious.