I started out using my paramount 300b's with the heresy II's. Personally I did not find the combination very good. Maybe a little honky, and very bass shy. They imaged very well, but the sound was just thin. The sound seemed to be coming from way back beyond the back wall of the listening room, very distant.
I wired the paramounts for 4 ohms, switched to the RF-7's and never looked back. The low impedance really has not been a problem in my setup. When I switch to the 205wpc parasound amp, I get a little more control in the lower frequencies but the paramounts put out just as much. I'm probably only using the first watt of eight at my optimal listening level.
That said, I would also state that the heresys were more musical, while the RF's are more analytical.