We took DS 4 at the time on Dinosaur. We forgot how very scary it is. DH and I had ridden it on prior trips. It is dark, loud and yes, you think you will be eaten by a dino at the end.
We felt like bad parents afterwards. Last year, DS was 5 and remebered the trauma of dino. He stayed with parents while we rode. We did not force him or even ask him to go on... We knew he would not want to.
BTW, there are other attractions you may not think are scary, like Honey I Shrunk the Kids and some of the other 3-D attractions. Loud and/or dark are pretty common with Disney attractions.
If your little ones are not fan of fireworks for example, they may not like some of the louder Disney attractions.
There are tons of great things your family will enjoy. DOn't worry, you know your kids and will have a great time!!!