While I am a very great fan of the single action, my current hiking and backup handgun is a Ruger Redhawk with the 5.5" barrel. Daned thing weighs a ton, and is not the most comfortable cannon I've ever packed. But, in the area where I sometimes hike, there have been problems with black bears and mountain lions. caliber of choice is the .44 magnum. Now, while I feel that cocking the single action in a real hurry isn't much of a problem for me, the advantage of the double action stand out over the single action in get it out and shoot fast situation. I used to compete in fast draw contests back in the early 1960s, so I am very familiar of what it takes to get that first shot off fast and still hit the target. However, whether I can do that instincively in a serious enounter with one of the above animals remains to be seen, especially if I only have a few feet distance. With my luck, I'd probably freak out and forget to cock the hammer.
FWIW, I found my Redhawk at a gun show, hardly used. Even with Pachmeyr rubber grips it was too much for the previous owner. I already have an S&W 629, but I like the extra beef in the Redhawk's cylinder for the very hot 300 gr. cast bullet loads I shoot. I also have about five Ruger single actions including an early flat top and an old model Super Blackhawk. I also have three new Model Super Blackhawks, one with Bisley handles, which I do find much better than the conventional single action grip for the .44 mag.
The .357 mag. should be OK for most problems, but if there is a chance of an encounter with something that just might want to bite,well I prefer the bigger hole.
Paul B.