Well had this on for a couple days now, and have only just noticed something about it today.
The original switch on the FZS was a two pin one, and the Kwak one is a 3 pin - luckily you can still get the wiring connector on the Fzs loom to attach to the kwak switch, and i didn';t think anything of it as the switch still cut out the sidestand if it was down and the bike was put into gear.
However, what i noticed today was that you actually have to put the bike into neutral to start it, rather than just squeezing the clutch in and hitting the button.
How did other people get around this, or did you more live with it?