I moved when I was 7, and it's a very distinct transition in the quality of my memories. I have tons of pre-move memories, including one confirmed by my parents as my 2nd birthday party, but they're primitive. No sense of time, just a jumble of memories that I can't place chronologically, and most are very brief moments. However, I remember the move and everything after it vividly and in chronological order.
I would suppose that the move made me reminisce about my old home during the period when my childhood memories were fading, and saved many of them from being lost.