Is your bike too nice to commute on? maybe. The Defy Advanced carbon is not as commutable as the basic aluminium Defy and has racebike clearances. Ride it if you feel OK about security but I would keep an eye out for a decent used commutable bike with wider tyre clearance and rack/fender eyelets. Drop bars are not really an issue. In the dry climate of SLC, fenders are not an absolute necessity but there may be days you prefer them.
I would keep a Defy Advanced for a play bike.