I wasn't getting consistent results out of my forehand roller. I have been trying to improve my backhand roller but for the past months the ground been either buried under snow or far too muddy to make real use of it.
If you want a reliable sidearm roller, use a fairly stable roller. A stable roller is much easier to predict, just like a stable air shot is easier to predict. The nice thing about a sidearm roller as opposed to a backhand roller, is that you can put a sidearm down much closer to vertical than a backhand.