Yeah I know it has more power, but we really need to decide if we're talking about street vs track.
Also if it's strictly street location might be key. Here in Illinois there's pretty much zero areas on the street where it would be advisable, or even necessary, to leave a corner at 14,000 + RPM.
Of course the extra power helps on the track, but on the street for the most part it isn't enough power to really put a gap on a FZ6. Something like a R1 on the other hand has enough power to gap the FZ6 on the street.
For the R6 to put distance on the FZ6 it needs repeated straights in between corners that are held at wide open throttle, there's not too many places I can think of to do that on the street.
So generally, on the street, the only reason to get the R6 would be for the suspension/cornering or for the styling.
For the track though, it's R6 all day over the FZ6.