Last october was DS's first time on Gringotts (2 months shy of his 8th birthday) .
He's scared of the drop at Splash Mountain. He rode it once when he was 6 and swore never again ... lol ... we'll see about that
He's a scaredy cat, but begins to get into thrill ride, but still tries to chicken out when getting close to the loading zones of Expedition Everest, and still talks about how he thought his brain would leave his skull while riding Rock'n'roller coaster ...
when you look at onride pictures of him , even as tame as 7 dwarves mine train, you'd swear he's absolutely petrified by fear ... (trust me he's not)
So, back to Gringotts.
He started screaming when the cart dropped. Then first turn he started to cry, with real tears and all.
DW held his hand and told him he could close his eyes if he wanted to. He yelled "no I want to seeeeeeeeeee" ...
He we still crying when he got off the cart. A Team Member even came to see if he was alright.
On the second step of the stairs, going down, he screamed "that was so cool, I want to do it again", then resumed crying ... well ... kids ...
We rode it several times since that first time.
Just give it a try. That's the only way you'll know. Don't make it look like you're scared that your child might be scared , or that you're scared for them... they will pick your emotions up, and be scared, not because it's scary, but because you're scared. And if mom or dad are scared, then "I" (child) probably should be scared too.
More often than none, we transfer our own fears onto our children