So here is a story for you all. A friend of mine was instructing at Portland International. It rained for two days, and his M5 driving student would just mash the throttle at each corner exit and let the DSC sort things out. It does. This frustrated my friend, and he suggested that the student turn DSC off, but also told him that they would do that in a turn where spin would be safe as he was CONVINCED spin was imminent. Novice student refused, and they went on their merry way enjoying the 400 HP beast with DSC assisted corner exits.
This student had fun, learned about the line, braking, weight transfer and some car control. That student went home with his gorgeous M5 intact.
My friend was driving his Cayman S, with DSC (PSM) off. He had lots of fun drifting through some corners (it rained two days non stop), and felt proud of passing Vipers and M3s. Though the Audis were unbeatable.
Towards the end of the day he was doing about 100 MPH in 4th gear. He was in middle of turn 9 (if you can call it that):
Throttle mashed to the ground, slight steering input, ~6,000 RPM. Basically a moment at the track when you would stretch your neck or your fingers, check your mirrors and gauges and then get ready for the braking zone.
Without any warning to this semi experienced driver, instructor, the rear stepped out to the left and the front grazed the wall (there is a wall on the right side along turn 9) followed by the rear. He had his car towed home.
My friend will always wonder how did he cause the crash. Did he get to close to the wall, did he hit a puddle, did he hit some fall leaves that he should have seen, did his leg twitch, was he too tired after two days and slow to respond to the spin, was he too comfortable and relaxed in turn 9...
So, to answer your question. If you have spare $20K to $50K and burning it would not make a significant difference in your life - by all means MDM off. But if that amount of money is meaningful or worse catastrophic to have to shell out tomorrow, keep DSC or at least MDM on.
And if you do turn it off, make a mental note that you have just doubled or 10x your risk (I do not know the multiplier), and make up for it with attentiveness.
Basically everything you do is risky, and in turn that much more rewarding. Same with MDM. Some people will use a condom and some people will take the risk... But think of the consequences of your decision, do not just go MDM off because your bestest friends in the world on M3 Forum said they do.
I personally will try to use it, if I find it too intrusive I will turn it off in the dry and when I feel super sharp. I will by rule run with it on during the last session of the day - the dangerous one - partially to force myself to slow down when I know I am tired. I will also keep it on in the rain. Spinning going straight when you just do not expect it scares the crap out of me as the straights I use have walls on both sides and I have seen cars in them. Spin on corner exit in 2nd gear I can manage, managing spin at 100 MPH is not something a skid pad exercise taught me. That comes with years of experience, and few cars that show scars. That just takes spinning at 100 MPH few times or I imagine oval experience when you are going very fast yet at a limit of adhesion.