While there is practicality in having all your SD/HD guns in one caliber, as the last two ammo/reloading component shortages have shown us, sometimes having a variety of calibers or not completely relying on factory ammo is more advantageous. i.e., similar platforms in different calibers.
When it comes to SD/HD we all have to do what we feel is the best. Our choices in firearms should be what we are most confident in, most comfortable with and most proficient with. Folks not into guns, with little interest and/or little or no practice with firearms can be as much as a detriment and risk to others in the house when they put a firearm in their hands as not. Real life is not like the movies. Those scenes of the Indians circling the wagons and the cowboy showing the pretty, petite saloon girl how to shoot his Colt for the first time, and then she immediately begins to pick off the insurgents one by one as they ride by on horseback is not reality. Also, just because one shoots a particular platform well and the gun fits their hand comfortably, does not make it so for everyone else that picks up that particular firearm. My wife is not into firearms altho I insist she know how to use them. While I am very proficient and confident in most all of my handguns, and she has shot most all of them, she is only comfortable with one.....and it is not the one I would pick if I had to narrow my collection down to one. IOWs, my minimal collection for SD/HD, if I wanted her to be safe and also able to efficiently protect herself, would be two platforms.
As I said, we all need to consider our needs and options when it comes to SD/HD firearms. All of us are different with different needs and scenarios. The OP has definitely thought long and hard about his choice and it may very well be the best choice for him and his. My only advice would be to make sure those others in his house know how to use that choice well and that they are as comfortable with them as he is.