Strike3, my wife's 3914 has a green front and yellow rear dots. All of my LE guns are green all the way around but I DO like the yellow rear for a couple of reasons. First and foremost BECAUSE the front sight is green and glows brighter than the rear your eyes are automatically drawn to the front sight. That’s what we’re taught to have in focus so it only makes sense that we would want that front sight to be nice and bright and in focus while the rear sights are a little dimmer or fuzzy.
Another feature that I feel more comfortable about (since my wife is not in law enforcement and doesn't get the frequent practice) is that in a night time shooting scenario there is very little chance that she would get her sights misaligned knowing that the sight picture is Yellow, Green, Yellow. For an inexperienced shooter in a dark shooting environment it is possible that they could point their pistol so that the sights are not aligned when it is all green. Of course I would prefer her to have a solid grasp on the pistol and “point shoot”, inexperienced shooters tend to rely more on their sights because they are going for accuracy and don't rely on their instincts with point shooting.
Some people also swear by the “bar-dot” night sights while others prefer yellow or orange rear dots while MOST of us get by just fine with three green dots. I had a conversation with a neighbor this very day on how hard it is to shoot with regular iron sights in the dark. And as I explained, "Once you start carrying a pistol with night sights you'll never go without back (to regular iron sights on a defensive gun)."
I hope this helps a little.