I find both approaches useful, it's fun to play around with how we look at a piece. For the most part I keep things absolute, using imagery here and there to help achieve an effect... When a piece is titled, it's often the first impression before I even hear the piece, and winds up influencing my imagery. Like when a book has illustrations in it, or on the cover, they influence how I see the characters in my mind (that really irks me, I never imagine imagery from a book the same way the artist draws it, and it makes some dissonance when I read).
I used to be strongly against sharing imagery of music, but now I think it can be useful to share the intended effect, or help non-musicians appreciate the music... So long as it's not concrete, imagery ought to be more symbolic than literal.