AWD system being heavy makes the car less balanced than the RWD. My G37 RWD handled much better than my Q60RS AWD does today and they now have similar suspension upgrades. It can help at launch but in the 1/4 mile it eventually loses out or is a wash due to weight. Technically it could assist some in cornering if you are losing rear traction and are not plowing.
In wet and snow it can be much more beneficial.