Ultimately the question was...is it faster?
That all depends on your version of faster. Is it easier to hot lap with ARS on, yeah I think so but the car is a bit harder to drive because the rear rotates a bit better. But on a lot of setups this can be the kiss of death and make the car way harder to drive.
For me personally I have found that ARS makes me slower overall over the course of a five minute run on medium/high bite carpet. I personally have found that the consistency of the standard rear end makes me faster over a five minute run.
I would say that ARS requires quite a bit of tuning and may be better on some surfaces than other.
Also, the tires you are running can have a direct impact on weather ARS may work better or not. If you are running tires that produce a lot of grip (sorex) and are very balanced than ARS may be a good option. But if you are running tires like Jaco that are more prone to grip/release than ARS could make your life a living hell.
It really comes down to the balance you have in your car and to consider how ARS may impact that overall balance.
I would say as grip comes up ARS becomes more useful especially if the increased grip seems to lock in the rear of the car.
It is still pretty early in the life cycle of ARS/ATS on the traditional touring cars, so time will play a significant role in finding the right settings for each platform.
I see ARS as a tuning option based on the track conditions and do not think it is a one size fits all kind of setup.