Honestly, I totally forgot about turning off the DSC... Maybe because I was feeling (wrongly maybe) that this all humming and electronics are saving my ass to get out from each pit (this 200m stretch going uphill with big pits, where the DSC was active almost all the time)... Damn it, I should have tried it without DSC!!!
About the HDC, I tried it the day before this long journey, while going down from the camping site. It works fine, but for me, I felt that it is letting the car go faster than it should. I didn't feel safe rolling with HDC taking control of the car... sometimes you might have like 3 meters of rocks-free stretch, so the HDC migh let you go a little faster, then you suddenly hit a bunch or rocks and the HDC gets "suprised" and activates... this "surpise" may send the car out of control... I don't know, but i felt that HDC works best in a uniform road with light slope... we all know that for steep slopes you have to go inch by inch and the HDC can't do that, and it can't see what's coming next to behave accordingly....
It's a nice gadget, but of limited application I believe...