I've seen both #4 and 00 buck used in LE roles over the last 30 years; I believe most outfits have gone back to 00 buck because of its superior penetration through light cover, against heavily clothed opponents, etc. I agree with this thinking.
#4 would not be out of place for indoor use; I'll stick with 00 buck for for the 'house load' for several reasons. I already know how it patterns in my shotguns. I already know it works against people. I just might, at some point, need to engage a dogass before he gets in the house; or need to take the fight outside. And finally, I know for a fact that when the dance opens, the only 'penetration' I'm going to be concerned with will be through valuable components of the person(s) who made me grab a shotgun in the first place. Nobody is safe until that matter is resolved and we'll worry about patching sheetrock and replacing carpets after the smoke clears, the 'hole check' and the head count is done.