On the main topic, I have always found, in general, that if I learn from the dots, I need them in front of me to play it - but if I learn by ear, I don't.

Uses a different area of memory I suppose.

Interesting, because my experience is exactly the opposite - once a tune's in the head and/or fingers it usually stays there, regardless of the whether the inItial source was the eyes or the ears.

If anything I think I file tunes by title, because I can sometimes play a half-remembered tune much better once I've recalled its name ...