So I wanted to just reply about this for anybody who has the same thought later and comes across this thread. I've had the FZ6 for a couple of days now, thought I'd update this with my thoughts so far.
The I4 in town - this whole you don't have any power unless you wind it up people talk about...non-sense. Even if I'm in 3th gear putting around at 4-5k RPM, if I open her up she starts picking up speed pretty fast. Sure it's not omg-holy-moly acceleration, but it's more than enough around town. And yeah maybe I only have a fraction of the max power on hand at low/mid range, but a fraction of almost a hundred is still a decent amount
But I have noticed, the engine really doesn't like crawling at single digit km/h. At anything less than 10 km/h, the bike is stuttering along and needs some clutch input to be ridden smoothly.
Also people aren't kidding about the heat coming from a bigger I4 compared to a little 300cc twin. The I think because the seat was narrower on the Ninja I felt more of it coming up towards me, but I never really felt too much of it on my legs, I assume this is probably also due to the fairings covering some of the engine. But man on the FZ6 I feel so much heat in the legs.