A number of priests I’ve known know some or all of the Eucharistic Prayers by heart. I was noticing the other day my new pastor pretty much not glancing at the Sacramentary while praying the Roman Canon of all prayers. I’m pretty sure he knows it from memory.
One priest friend of mine related the story (about twenty years ago) that during a retreat/home Mass, somebody snatched his text away and said he was a good enough presider that he didn’t really need it. He didn’t, but I think it was an alarming experience.
Anyway, sit in the purple chair and advise your pastor: is it good to know all the EP’s without reading the text? Is it a distraction? Does it affect the prayerfulness of the priest?