I also had the LeafGuard gutters installed apprx 8 yrs ago, after having endless problems with pine needles, plus the usual junk. Tall pines, cherry and oak overhang the house. My old gutters would block in weeks, sometimes days, after cleaning. The LeafGuard gutters have not blocked yet. The installer said when they block it is usually due to a bees nest. I have not had that problem. Also offers free cleaning if they block.
The first caveat is that when the rain is really heavy, as in torrential, the flow of water is too strong to make it perfectly around the bend into the collector, and some water lands 3 feet or so from the base of the house. This is particularly true where there is a joint in two rooflines, causing a channel. Still, the benefits to me FAR outweight the detriments. In fact, I am so happy with this improvement that I actually think about my gutters gratefully from time to time.
The second caveat is that they were very expensive, esp since I have a long ranch.