I think if you like rock n roller coaster you will be fine on Gringott's. I do have one suggestion to make though, there are 6 rows total, split up between 2 cars. In each car row 1 and row 4 are the lowest point, rows 2 and 5 are a bit higher up, and rows 3 and 6 are the highest (it's to allow everyone to see the screens). I am 5 feet 5 inches tall and if I sit in rows 3 or 6 my feet do not touch the ground and I therefore cannot brace myself for the turns and the ride feels much jerkier. When I'm in the rows 1 or 4 I can plant my feet firmly on the ground and brace myself and I have no troubles. In rows 2 and 5 my feet touch the ground but I can't brace as well.
Because rows 3 and 6 sit up higher they allow more leg room and are known as the "fluffy friendly" seats. The seats themselves are not wider nor is there more room between the seat and the lap bar, they just have more leg room. A big and tall person would do better in those rows but a big and short person does not.
Because I'm bigger round the middle I found that I was constantly getting put there by the workers even when other rows were empty. It doesn't offend me, the worker's are trying to make me more comfortable and they automatically put bigger people in those rows. Since I dislike those rows so much I have learned to tell the worker who asks how many people in your party "I have 2 people in my party and I fit in every row." They will then usually seat me in the next available row instead of putting me in the back.
That may have been too much info lol but hopefully it helps. If you are my height or shorter- ask for row 1 or 4 so you can plant your feet and brace for the turns and you shouldn't have a problem. In my personal opinion, row 4 is the absolute best row, it's a front row feel but you are back far enough to see everything so I always recommend row 4 for a first ride. If you ask very politely, the worker's are usually quite accommodating with row requests.
Also depending on how many years ago it was that you rode Forbidden Journey you may want to give it another try. They have toned it down a good bit and it isn't nearly as jerky as it used to be. I don't know when exactly they did this, I just know it isn't as jerky as the first time I rode it in 2015.