Unless your primary goal is to own recent equipment (rather than a goal of owning the best equipment for your needs) then you should judge lenses only on their performance and functionality, not their age. The 35XL is an excellent lens regardless of it's age. Is it possible that a year or two from now Schneider will announce redesign it to be even better? Sure. But if you look at their recent redesigns the newer lens will also likely be twice the price. 28XL is also an excellent lens.
One consideration is that neither of these lenses is especially well suited for use on an 80mp digital back. So if such a back is in your near or mid-term future than these lenses are not right for you, and you would want Rodenstock wide angles instead.
Another consideration is whether stitching and/or cropping are acceptable methods for you to make a specific lens longer or wider (acceptable meaning it won't significantly interfere with your ability to make the images you want to make). Of course to properly make that consideration you'd need to know both in theory and in practice what a certain lens can "flex" to via stitching and cropping. We often make custom illustrations for our customers showing a specific lens (given it's focal length and stated/usable image circle) and how long/wide it would become with stitching and cropping.
The 43XL has a huge image circle which makes it very flexible. See below a custom report I made for you.
Basically a 43XL with an IQ160 (or P65+) can be:
- a 52mm when cropped down to 40mp [35mm FF dSLR equivalent]
- a 43mm with a single frame (duh) [28mm FF dSLR equivalent]
- a 32mm when stitched with two shots [20mm FF dSLR equivalent]