I figure a dowel on a string is what the rollotube amounts to.
The Slider is much larger that a wedge, and fills the kerf evenly, allowing your to finish your cut without pinching the bar at the end. That's where the saw chips like to jam under the chain.
Push the saw through, start your next round, and slide maybe. Maybe you're be too far down. You might have to hang your saw instead of the double block bucking.
Been a long while since firewooding down a tree. A triple firewood piece will Magic Cut with a vertically short facecut (undercutting the COG). You only lose a small wedge, so the piece is still almost normal.