The reach difference is really not huge, (which will be apparent once you see the pictures), the main differences is the fact that they are lower and flatter, and your wrist will not be as twisted as the stock bars.
You have to reach forward a tiny bit more, but can still sit upright comfortably if you chose to. The lack of twist in the wrists does make tucking in/lying on the tank a lot more comfortable.
Since my bike is naked i will often lie on my tank when doing long trips on the highway, it is surprisingly comfy!
For me the biggest advantage of the FZ1 bars is the fact that they make steering input a lot easier.
For some reason the fact that the bars are flat and straight makes steering feel a lot more direct and controlled, like you have to put less effort to flick the bike.
The bar change didn't feel like a massive thing when i first did it, i mostly did it for fun and to try.
I recently rode my friends stock FZ6 and the bars felt horrible, i felt like i was riding an oversized bicycle.