The FX series is flat out awesome in hull design.
I have the previous Ultimate 12 and it is extremely
stable. The Ultimates are super customizable, as
well.
If money were no object, I'd probably get a Hobie,
but since that's nowhere in my future, I would jump
at the opportunity to buy an FX12.
Secondary stability is fantastic, as well, given the
pontoon design. I have no problems standing at
all.
Additionally, no, I don't have a rudder, but I did
rig mine with a MinnKota C2 30 that I steer with
the foot pedals, and I rigged a control box on my
left hand side. Works awesome.