I think you're best served by choosing a particular pistol and load, then sticking to it and practicing.
Taking a step back, and examining the OP's idea, I think that having different types of ammo for different situations may have some utility (it is usually pointed to as an advantage of shotguns), but for a self-defense oriented handgunner, it isn't a good idea. Overthinking the basic problem of personal defense by trying to include unlikely scenarios complicates the issue.
The overwhelming majority of valid self-defense shootings are quick, stressful encounters that preclude the relatively cool decision to switch to a specific reload based on a tactical problem. I'd rather have a simple, reliable system, then solve whatever tactical problems arise through marksmanship, retreat, calling for help, etc.
That said, having a reload of FMJ probably wouldn't hurt. I'm just saying I don't think you would ever need it.