We had Leaf Guard installed on a brand new two storey house in Sydney and found it useless. The leaves still build up on top of the mesh.
The only way of clearing them was to hire a gutter cleaning service, who charged extra because the leaves get stuck in the mesh. Leaf guard people told me that there were too many trees around the house.
We solved the problem by getting another leaf protection provider to remove Leaf Guard and replace it with one that works. Its been in for 1 year now, with no build up, works perfectly.