Your carry gun should be one that you can conceal and handle easily and shoot accurately. If you can do those things with your Shield, there is no reason to use a weapon that fires the less powerful .380 round. As to home defense, since concealability is not an issue, I would choose the highest capacity, most reliable pistol that you can handle easily and shoot accurately. Try a bunch of 'em, 9mm, .40 caliber, or even .45 caliber at your friendly local gun range, and pick one that is best suited for you.
Good Luck!