I don't have to deal with pine trees but I installed
EasyOn Gutterguards (I got them from Costco, ordered them online) about 2-3 years ago and I have to say, knock on wood, so far so good. The only thing is, is that I get a collection of sticks/twigs up on the guards and I get out the ladder and clean those up once a year but the material is a super fine micro mesh and it does a very good job from what I can tell and I'm not cleaning gunk out of the gutters.
Before that the previous owner installed those crappy plastic guards with the circular holes and they were all but useless. In fact, I would go so far as to say worse than nothing because junk got in there, small seeds and every single year before winter I would clean out baby trees and the worst smelling crap in the world out of the gutters and I STILL had to remove those guards and put them back on because I kept thinking "well, it's better than nothing."