Shot both. I liked the feel of the 4" better because it seemed to point faster and more naturally. But I believed that the 6" would give me a slight accuracy edge, and bought it for that reason. I'm keeping it, but looking for a nice 4" to go with it.

The 6" is heavier, your wife may enjoy the reduced weight associated with the smaller 4" barrel, so I'd go that way, but the truth is that there is no bad choice here.