"Upgrading"

Recently a friend of mine traded her clustered marquis cut engagement ring for a 1-carat canary diamond. So I wondered if other brides had chosen, or will choose, to "upgrade" their engagement rings. My husband and I have not discussed the matter, but I assume that our 5-year anniversary might be a fitting time to change our bands or consider getting a new bridal set. As always, I love to hear from our you--what do you think of ring upgrades?