Aha. That all makes perfect sense. I wouldn’t personally have so much duplication, though, and get shift & modkeys on the thumbs to make easy combos, but it’s fine if you want them elsewhere. Do you use function keys that often? I just realised I use them so much I forgot to setup a layer for them, but that at least seems like it could go on one of the pinky keys. And a rotary encoder there would make heaps of sense.
That could break some peoples' dotfile management, e.g. symlinks or git repos. I'd say deprecation notice and reading from both, at least for a while, is better.