I've been down this road..... I'll tell you, there is no such thing as maintenance-free gutters of any kind.
I had trouble with the little "worm" things that fall from oaks and such in the spring. They clog almost anything....
Mastershield guards were a recommendation from vob villa way back when, and they've done an admirable job for me for years... Just make sure someone installs them that knows what they're doing.
Leaffilter Contact is Doug Turnau at 803-225-5570 or mrworldcat@msn.com
These folks were at the Spring Flower and Plant show at the Farmers Market. Consider them.....I recommend them myself.