Yes and no. Initially no, it doesn't benefit my memorization, because my process is based on score study, not listening. But after memorizing, I do play by ear. I can describe the progession of events in theoretical ways, but that's not how I know what to play. I hear it playing in my head and copy it back to myself. But even though I can tell what notes I'm hearing, I'm paying more attention to the relationships, I guess, because I can play pieces in other keys. So in that case, I'm not following "hear a G, play a G," it's more the shape of the music. I don't know, it feels like the piece works the same way in my head no matter where I play it. My teacher does the same thing (better).
When I observe conversations about perfect pitch, I worry that some people who don't have it feel they're lacking something, and I don't believe they are. There are so many ways to have a good ear: varying degrees of detecting pitch/harmony, an ear for timing, for nuance, timbre, style, balance, and overall taste. The person I go to for interpretation has an incredible ear for style, timbre and characterization in music, no way has perfect pitch but is certainly one of the best musicians I know, and hears nuance that totally escapes me until it's pointed out to me. I know what key/chords I'm listening to, but he hears EVERYTHING. I'd like to be more developed that way.