Those holsters from "Simply Rugged" look real nice.
I have two strong side hip holsters and one verticle shoulder holster. When I lived in S.E Alaska I used the shoulder holster, an Uncle Mikes SideKick, all the time. It is great for hiking, keeps the gun from bumping the pack frame, the weight of the gun is more balanced.
I still prefer the shoulder holster, but now I use boats more than hiking and thats where I use the hip holsters, and berry picking. I have a leather S&W open top with a safety snap and a DeSantis nylon for rainy days.
I also like to back country ski and use a tanker syle from El Passo Saddlery. The Chesty Puller style from Simply Rugged are LOOKING PARTICULARLY ATTRACTIVE. They can be worn on the outside and centered.