I am adding my experience of hill starts on ice and snow . ice is very challenging . snow does not give much problem . the cars have winter tyres .
I have found the best traction with the system on . normal mode . power is reduced after some serious wheelspin , usually a few minutes of spinning .
if you go easy on the power some or all wheels can spin slightly with dtc applying enough brake force to assist traction . the cars do move uphill

I tried hill starts with dsc off . this results in no uphill movement . often the cars slide back downhill with the wheels spinning trying to keep going uphill .