With lighter recoil, higher cartridge capacity, and ease of handling combined with adequate power, the .223 has become much more popular as a home defense weapon of late. However, as you've noted, it does carry the "assault rifle stigma" if you have to go to court over it. I've seen it happen. It will be important to be able to articulate to a jury why you chose that gun, and to be able to educate a dozen laymen who don't know from guns that they've been BS'd by the media about Evil Black Rifles for a generation. Choosing a Mini-14, which seems to carry a milder image, makes sense; I've found that a conventional stock as opposed to an AR15-type configuration is also easier to keep in your possession in a struggle for the gun.
Psychologist Glenn Meyers, who posts in GT occasionally, has done some jury testing work which shows that jurors do indeed respond negatively to "assault rifles." Glenn and I will both be teaching at Tom Givens' National Tactical Conference and Polite Society match in Tulsa next week, and I'll see if Glenn can't provide me with a link or two to share here.