When I had the 400s - the steering on them was very smooth and lighter than the 430 - part of the reason is probably the narrower tyres
Since having the 430 I have never got the steering perfect:
It is slightly heavier to turn than the 400s
here is more road feel especially uneven surfaces
It has a tendency to jerk a little when going over bumps and uneven surfaces
I tend to feel a slight wobble when going over uneven surfaces
I have so far replaced, tie rods, ball joints, steering rack bushes and gone through different brand of tyres - but never go it 100%
I think part of the reason is the profile of the tyres
The pre-facelift ones are smoother with 17 inch tyres