Thanks Indagare for this thread as it made me reconsider my single class build.
So I’m trading out a 5th, 6th, and 7th level slot, 3 prepared spells, an 18th level subclass ability, an epic boon feat, and a capstone for a much slower progression and a three level dip that raises my primary stat by six, gives me an extra skill proficiency, a skill expertise, a better telepathy, and the ability to have proficiency in all three mental saves.
I think many/most wouldn’t do this dip, particularly due to the slower progression, but I know it’s better crunch-wise for my specific character and worth rationalizing the fluff.