if you were not trying to get preg, have the d&c. going natural can be better emotionally when you do not want to feel worse/sad in the doctor's office or if you are just hanging on to hope. a natural miscarriage can take days and it can come on in the middle of work, etc and it is painful/messy/scary. in the end even if you go natural, after a checkup they might do a d&c anyway if not enough tissue has passed.
I just had a d&c on Wednesday it was not painful at all my doctor also gave me meds to take for 10 days to prevent infection sorry I don't know the percentage but I have hear that a d&c is the safest way to go no pain and they get everything out at once I personally think you should go with the d&c so you won't have to endure all the pain going natural but in the end it is your decision I hope I was able to help you in some way