I've done music a long time on just about everything, I could not get into ableton's interface. I feel bad because I remember others saying that of other programs and thinking, "all this stuff is interchangeable, you should be able to work in anything".
Everything about that program confuses the hell out of me, but i will say this, guys who know it, can jump in it and work so fluently it's made me envious.
Not trying to divert anyone, you should definitely demo it, but if you know FL well, why not stick to your guns. I think alot of people jump from Fl because of how it's perceived to be a novice program by guys who shouldn't matter.
I've made some of my best music in FL, I doubt anyone who's utilized the tools in FL while using it that has jumped to another program can honestly say different.