I dunno. There is 4 fx1s in my tiny town. All the dudes talk about how squirrely they are, and how bad ass they are, more than riding.
They arent hard to ride. I hopped on one and stabbed it totally under within 100 ft of riding one. Seems to be alot of people think they are hard to ride? They just dont handle well, there is a difference. They are extremely similar to a 550. Ride almost identical IMO.
Dont get me wrong, I started on a 550, and think yamaha makes a superior machine. But I do not think the fx1 is a good ski for freestyle. I want a wide tray, thats a BIG thing. I think my SN tray could be a lil wider. Who wants to cut up their pump tunnel along with holds and reinforcing. The fiberglass bottom isnt THAT big of an issue since most skis get reinforced anyways I guess, but the motor mount issue is a big deal. The ski itself is narrower, thus it will sink deeper and easier on landings, another BIG thing with a freestyle ski. People say the sj is a boat, I kinda agree, i can stand on mine in open water with it off. Thats a bad ass stable machine if you ask me. The hull on a sj lends itself to more pop IMO even tho it weighs more, but again the pump could be a big factor here. Lets not forget the aftermarket support.
What all that boils down to for me is that a sj is a far better entry level ski into freestyle. Less money to do far more, more reliably. Its hard to argue the facts, but in the end its gonna boil down to your preference, and what you like.