What is the difference between using an Eco router vs. putting my existing router in a Router Guard or equivalent Faraday cage?

The problem with a router guard is that it works in both directions: Not only does it attenuate the transmitted signal, but it also impairs the reception sensitivity of the router. The Eco router allows a 90% reduction in transmission power without affecting signal reception. It also eliminates the 10 Hz wifi frequency, which a router guard cannot do.