Quite often, elastomer composites are selected to have two or more polymer components with the intent to control energy storage or loss at different temperatures. However, the desired performance from this approach can be negated when the two polymers selected have similar solubility parameters. Further complicating the design of composites for specific dampening applications is the possibility for preferential filler location between polymer phases and heterogeneous cure. These phenomena have been studied with filled homopolymer and copolymer blends by dynamic mechanical testing as well as scanningprobe microscopy. The sensitivity of material selection and processing on energy storage and loss are discussed.