I agree that the 6" lift looks great - it's one of the weird things about the FJC: the much bigger tires and much higher suspension make the vehicle look better (too much body for the wheels in stock version, for my tastes), but the design makes it REALLY hard to actually implement these things (e.g.: front axle too far rearward for big tires). I'm sure the 6" lifts (I guess they usually combine a 3" body with the 3" suspension extension?) are stable. My only problem is that when you add in the diff drop to make the CV angles appropriate, you don't again any ground clearance

All you get is whatever extra you can get out of the tires. I think if I were really pondering the 6" lifts, I'd probably end up asking for Sol's design specs on his Demello-implemented solid-axle swap