This would push users toward local posts (especially on smaller instances) while still supporting a better distribution of user engagement over the threadiverse. And if you don’t trust that it was implemented correctly – you can simply check it by counting the amounts of posts against your chosen probabilities.
Edit: changed feed name to mixed-feed
I often do that but often enough I just stay on local out of convenience. It would be great to have just one feed for that where you can get both