well on the trackdays I've been at I've noticed that ATTESA only sends power to he front wheels when the steering is relatively straight, ie not when the wheels are turned, so its not like you get AWD around a corner. But what I dd find with HICAS on say motorkhana days where you do a lot of turns was that the back would start swinging out around a corner, which is normal for a RWD car, but then HICAS kicks in twitches the back wheels, and makes it really hard to control. Took the HICAS out and I could countersteer and feed the throttle and control the oversteer... which meant that I could get the steering straight quicker, and therefore get on AWD between turns... instead of simply fighting the steering.
HICAS is great for day to day driving, highway driving etc, but on the track, and in the wet can make things bery hard to predict.