6 rounds of cons. One may do the trick. Or two. Or all 12 might be needed to get the job done depending on distance attacker and about a thousand other variables you have no control over. I suppose its up to you if you wish to lose a couple of ounces vs loading six rounds and wind up wishing you had more if you need it.
Biggest con of all is the one sure one. If you will need your pistol, and when you will need it fully loaded in the worst possible way to defend yourself and your family will not be up to you.
Your choice though. Be safe.