I'm in the market for a 20ga shotgun for home defense. My wife is not very interested in handguns (shooting or carrying them), so I would like to have an option for her as a last resort if something were to happen while I'm not home. So, it seems that either the Mossberg 500 or Rem 870 are out there and both come in multiple lengths. Planning to get either 18" or 20" at most. Anything else I should consider? Thanks in advance.