I've said before that I've limited myself to two guns, a Glock 19 and a Glock 26. The OVERWHELMING majority of the time I carry the 26. In fact the only time I carry the 19 is when my wife and I go to church or when I go out with my wife during the day.
My rationale is first that I should carry the biggest gun circumstances permit and second because the 19 is the easier of the two for me to shoot well. Having said that I don't think I really shoot that much better with the 19 than the 26 and of course with a 19 reload I'm not giving up any capacity. I don't base what I carry on any threat assessments or anything like that, if things are so sketchy that I feel the need for a bigger gun I don't go.
My primary reason for considering this is simplification. I don't have to decide, I don't have to lock up the one and get out the other, I don't have to switch holsters. The only time there might be a minor hassle is if the holster for the 26 is already on my work pants. But none of those are performance issues.
Any input is appreciated.