I purchased a home in which leaf guard was installed. The previous owner obviously had money to burn, and could not be bothered to research the product.
I would never buy such an expensive product without thorough research.
It simply does not work, the concept is unsound even when properly installed. In my case shoddy workmanship aggravated the situation. Their lifetime warranty is a joke. They do not repair the broken and clogged gutter, and wriggle out of any responsibility.
If you decide to install it, expect to have to service and maintain it yourself. Chances are that you will end up ripping it out and replacing it with a gutter that works.
Review about: Leafguard Repair.