I have also had a chance to test the various driving modes a lot in slippery conditions now. The early DSC systems in the E46 did not suit my driving reflexes. When the car stepped sideways, I instinctively corrected with pedals and steering wheel. The DSC also tried to correct with the braks. In total, it was always too much. I could easily lose control of the car after a series of overcorrections. I found it more dangerous to drive around with it enabled than disabled.
In the F20, the DSC is a lot better. It no longer overcorrects. I can still drive faster with DSC Off, since DSC brakes too much (even in Sport+), but I consider it safe. I can leave the systems enabled in public traffic.
The Sport+ setups is biased towards oversteer. It is almost impossible to make it understeer in slippery conditions. It does however allow the back end to step out quite a bit, just the way most BMW drivers prefer.