I think you are looking for the following
So last year I bought 2 bikes: 2008 Fz6 and 2009 650R Ninja. Both brand new.
First, I love both of them. They have their little charms but before talking numbers and quality, they are made for 2 different types of people. Tall people or petite women

I am 6.1 at 210 pounds. 650R is small and not as comfortable. My GF is 5.4 and the 650R fit is perfect for her while the FZ6 is way to big and completely inaccessible.
Quality: 650R is good and has the looks as well. But consider the FZ6 frame that compared t 650R is one piece cast aluminum and no hundreds of welding points between every tube possible that makes the 650R frame. Just that already shows that FZ6 is in a different category and you get a lot more for your money.
Power: Yes, the twin is a no drama all around. And the sound is actually very nice and deep, it really sounds like a beast. That twin you don't have to rev it up to get going. Actually, I never checked the RPM meter to see where I am on that respect. Just a very nice linear power for everyday use. Nonetheless, the FZ6 is actually very OK at low speeds, but yes you do have to rev it up more. Is that a problem? NO! At the end, you drive a bike and it is just a different style, no better or worse. It is not for nothing you have 12k RPM on 650R and 16K RPM on FZ6.
At the end I suggest to go with the one that fits your body first. Style of riding? Both are the same 99% of the time as 99% of that time you are around town going about your life. The rest of 1% doing bad stupid stuff on the highway :BLAA::spank:

like see the MAX you bike can do in a straight line and stuff... well, if you have the 650R then you would wish you had the FZ6
FZ6 has a plus on built quality (frame and the known qualit of YAM)
650R has a plus on looks (2009 has integrate lights all arround and already comes all in white lenses that set you up $200 of mods to do the same on FZ6 and still will not get the same slick result as on the 650R)