As far as leaving the rear engaged under braking, HPA says it all for me:
Originally it was implied (maybe even stated explicitly?) that our Gen2 unit + switch in "race" was equivalent to the G1 Competition ("orange") controller, including the engaged rear whilst braking.
The default behavior for the Haldex (in "sport") would still disengage the rear, which is great for the street or people who don't know car control.
The whole point of the switch + Race was to give us further control over the rear. I agree with HPA - I'd rather have everything stay engaged (for balance reasons) than have the Haldex deciding that it needs to open the rear clutch. I also autocross and run the occasional track "Fun day" though, so I am not everyone.