I have the kind that you stuff inside the downspout opening in the gutter, and they work well to keep the pine needles from clogging it up. I'd think that, if you have a heavy leaf fall, a complete gutter guard would result in a heavy layer of leaves on top of it, with the resulting reduction in water penetration to the gutter itself and ice buildup on/at the roof edge. Ice is never a problem here, and I try to forget my years living in snow and ice country..