Gutterfilter was good for about three or four years. Then the gutters began to overflow because the filter is clogged with dirt and grit off the roof. I have contacted them, and tried phoning. No good.
So today I tried to fix it myself.
1. Clearly, the product itself has deteriorated due to sun exposure.
It has changed colour from black to grey, and is brittle. Many of the "cells" of the filter material have collapsed or broken apart.
2. The 'hidden' side of the filter is thick with black goo, presumably leaf debris, mould and mildew.
3. I tried to wash the filter by forcible flushing with a hose, and all sorts of goo came out, containing roof shingle sand and debris.
4. I hear that there is now an improved product with a different configuration, added fungicide (don't see how that would work for very long). But as I grabbed handfuls of debris/mould/shingle sand out of my gutters, I doubted that any of that would be enough.
Conclusion This was expensive stuff and should work better. I'm very disappointed in the product, and since I can't get a reply from the company I can only assume that they know the product is not as good as they said.
It would be cheaper to pay someone $200 a year to come and clear the gutters after the fall.