I can see absolutely zero downside loading the disc. While Garmin is superior, and so are most other manufacturers navigation systems, since you bought the feature, might as well get the benefits. If you use it occasionally, it will do a decent job.

You will only gain with the disc in. Traffic information and current location information. I have my right hand side of the display that shows the coordinates, direction, and current road and town. I always find that to be useful.