I wouldn't say 100%. Snakes can and will bite when provoked. No matter how good natured a snake is, there is ALWAYS the chance it could bite. Nobody could ever be able to guarantee that their snake won't bite.
HOWEVER, I trust my Dumeril's way more than any other snake that I have. As long as you keep the head away from little kids, you should be fine.
I had my Dumeril's out once and my friend and her baby popped by. Bailey is 6 months old and was really enthralled with my Dumeril's. Of course I had my hand around the snake's neck the entire time just in case anything did happen, but Bailey was petting David Bowie like a 6 month old does...sometimes not the most gentle, but I knew she was safe since I had such a good handle on the front end.
Just be careful, take all the precautions you can and you should be good.