I have had both. FZ6 and FZ1. Trust me, the extra weight from the FZ1 is not worth it. The 600's are plenty quick enough for the roads. In most case's too quick. My FZ6 demolished most fast cars. Loved the torque of the FZ1. But she was a heavy unit.
I now ride a CBR600RR. It's really light, and smooth as silk.