That would depend a lot on whether you wear it with a real stiff, reinforced gun belt, or not. A regular belt would let it sag, and the high ride and the law of gravity will do the rest.
I've got a Wilderness 5 Stitch that I've found to be more than adequate for both IWB and OWB with bigger, heavier guns. I'm just worried about the holster not holding the gun in tight to the body.
This guy makes some of the most beautiful and sensibly designed holsters I have ever seen. I am going to ask him for a second clip tab with a patch of Velcro hook in place of the clip, and a screw and nut so that I can swap them. I'll put Velcro loop on the back of my belt where I like to carry and have the ultimate in concealment.
Here is his website. This holster is featured under Tuckable.
The website is a little confusing, but you will get lost for hours poring through albums of hundreds of high def pictures, clicking to enlarge them, and saving them to your Wallpaper folder!
The picture shows a 1911, but the holster for a CM9 would be much more compact. It is deep molded for a perfect fit to the gun, smooth on the back and fully leather lined, all for $45 delivered!