Owning a 2012 GT, I can say the live axle is not a factor worth spending much time talking about. Plus what they have done to refine it over the years is pretty impressive. Its very predictable.
Now when it comes to overall suspension - spring design, camber, strut bump and rebound etc., they have also done very well over the years, although there is still some improvement to be had, I think. However I'm not entirely sure because I have the base GT suspension and all season tires, not the track option,as I'm no longer going to the track. In my opinion, having owned and/or driven or instructed in just about every car, Audi and BMW are still well ahead of other manufacturers in overall suspension tuning and competence.