I often pocket carry my MK9 (in a pocket holster). How it works depends on which pocket we're talking about. It works well in a coat pocket, for situations where you'll be keeping the coat on for the entire outing. For pants pockets, it depends on the "fit" of the pants, and the depth of the pocket. I don't care to carry the MK in the front pocket of baggy pants with deep pockets; there is too much "thigh slap" while walking at a good pace. For snug fitting pants (such as jeans), I carry the MK in my back pocket (palm to butt draw), with an untucked shirttail. The gun is high enough, so as not to interfere with sitting, but almost impossible to draw while seated.
Bottom line: if the gun is secure enough, you don't notice it's weight; if the gun to too free to move, the weight becomes annoying.