There's a lot of UX work to do for SRS. Do you have a sense of how well the ideas behind Humane SRS translate outside of language learning? I imagine the main challenge would be identifying a steady influx of new cards.
I agree that gains in scheduling accuracy are fairly imperceptible for most students. That's why, over the past few years building https://rember.com, we've focused on UX rather than memory models. People who review hundreds of card a day definitely feel the difference, doing 50 fewer reviews per day is liberating. And now that LLMs can generate decent-quality flashcards, people will build larger and larger collections, so scheduler improvements might suddenly become much more important.
Ultimately, though, the biggest advantages is freeing the SRS designer. I'm sure you've grappled with questions like "is the right unit the card, the note, the deck or something else entirely?" or "what happens to the review history if the student edits a card?". You have to consider how review UX, creation/editing flows, and card organization interact. Decoupling the scheduler from these concerns would help a ton.