To be honest, unless you've ever really driven your M to the limit with the DSC off on a race track, you shouldn't really attempt to on the road. I agree with Karrussel, I love to drive with the DSC off too when i'm enjoying the cars potential. It encourages you to use more thought, more control, and have more respect for the beast that you are taming.
Senorfunkypants is right too - an experienced/trained driver with DSC off, over inexperienced with DSC on, any day of the week. Ultimately you are your own limiting factor, if you're driving outside the limits of the car, whether that be with DSC activated, or deactivated it's going to bite you in the bum! I'm not saying a good DSC system isn't going to get you out of trouble, but it's not be the saving grace in every situation. I'd encourage any body with an M car to get themselves on to a trackday and see exactly what these cars are all about...