When I was a young kid, I knew one pulper that used one in the yard. Skidder would drag tree-length stems, yard guy would unhook and cut sticks, then the skidder yarded. This guy liked the bow best for this work. If he was dropping trees, though, he didn't use it.
There's a hook on the bottom that must be up tight to the log to avoid accident, and most of them had a guard over the top of the bar. Watching this guy work that bow, made it look easy. It looked a little like he was stabbing the logs with his saw; he never pinched, and was so smooth and fluid in his motions, always stopped within a fraction of the bark on the back side. I tried his saw and it wasn't near as easy as it looked
I hear the bow guides were far more popular down south, in the pine plantations. Now that work is mostly handled by big harvesters, so the bow guide is probably pretty much dying out.