I have two holsters for my Shield 40
Winthrop IWB
This holster is extremely comfortable. I needed slightly larger belt loops to go with my 1/4 thick (1/2" wide) gun belt and Winthrop sent out a pair immediately. Plus the snaps only open one direction from the top, so there is no way a belt can be pulled to open them.
and just received yesterday my Remora 5ART-SS-Leather holster for summer shorts carry. My Shield 40, when fully inserted, is gripped in place. (If I hold it upside down, it stays.) With very little effort, it pulls free and is completely unrestricted the rest of the way out. In my pocket, the gun is drawn with ease. And with the little bit of experimenting that I've done with using it as an IWB - same thing.
I have to admit, the Remora is much more substantial than I imagined. I cannot see how this holster would ever wear out.
It looks just like this one (except you can't see the leather)