... we know it will have a pdk gearbox. IMO, it will be an improved version. Add to it the specs of the 991, enhance it, basically, it should be the best porsche ever, on the pure side point of view.
The turbo will always have the latest tech evolutions, the 4W directional is a real novelty and surely a plus in handling. But from a mechanical point of view, power is coming from turbo's, it will never be the same as pure power coming from pure mechanics 
So, big dilemma in choosing between the new 991 turbo and the new gt3.
The mind will say turbo, for the daily use, the comfort, the power, the 4wd, the 4WDirectional, and for the ease of exploiting all that.
The heart will say gt3, because its pure and closer to the spirit of what a real sports car should be: Emotions
I think i might take the gt3, when it comes to triggering when i hesitate, and think about the compromise and the best overall decision, there is always a little voice inside me that whisppers " if you wanna do things, do them right", in this case, no compromise: GT3.
Now we never know, all those nice words might vanish the moment i test drive the Turbo
)
Did i tell you that i love the 991?
)