Tbh I can't see much point in using it with FL. I mean - if you find yourself wanting a load of buttons that you can map in FL then yeah - it might be just what you're after. But part of what makes it cool is that in Ableton the device automatically sets itself up to control various aspects of the DAW, as well as controlling Session View's clips.
I do find myself using it more often whilst producing when I'm sketching out ideas, it's nice to toggle clips and and do other things without having to bother with the mouse, and obviously the lit buttons make the work-space look cool when the lights are down
. I've also got a lot of stuff mapped to User 1 mode - like transport controls, markers and a few devices, which I usually set up as the track progresses.
But I'd say if you have no intention of doing live playing / jams / improvising and don't need so many buttons, don't bother with it. Especially in FL, as you're missing out on a lot of the stuff that using it with Ableton would offer you.