Oh Jasper,
I hope your DD8 reads this. My DD now 11 and DS now 9 first went on this ride in 1999 at 6 and 4. My DS is quite daring and will try anything. He loved the ride. My DD is a tentative as they come. She hates loud noise and is intimidated by many rides at Disney because they are soooo loud. She will absolutely not go on the TOT again and I certainly will not ever to make her until she is ready.
We usually highly encourage our kids to try a ride before liking or disliking it. On the Haunted Mansion we talk in great length about the fake graveyard at the beginning and then the stretching room. I will say that my DD(almost 12), will still close her eyes in the stretching room to go on what she feels is one of THE BEST RIDES, DEFINITELY DO NOT MISS, at Disney.
All kids are different. Even though my DD is very tentative on rides she loves the 'show' once on the buggies. Our family makes a contest out of who can make the best witch cackle during the ride.
Jasper's DD8, my advice to you is try it. The stretching room is a little wierd. If you are uncomfortable close your eyes. It is VERY short and you are then on to the air-conditioned buggies and the fun.