low power filters using polyphase decomposition

Polyphase decomposition is a method of transforming a filter into k filters running at 1/k of the sampling rate. The benefit of polyphase decomposition is that reducing the sampling rate of a filter by a factor of k, reduces the power required to implement the filter by a factor of k^3. Of course if we require k times more filters to implement the system, we may only get a k^2 power benefit. I have to play with some real systems to get data.