I will admit Sum of All Thrills is much tighter. Somehow it just didn't freak me out as much as MS-orange. I was so worried about squeezing my hips into the Sum Thrills that I forgot to pay attention to the shoulder harness. Plus, MS puts a lot of pressure on your body, Sum doesn't.
Sum has a "tester seat" off to the side of the ride so you can see how the seat feels. Look for it. I didn't see it until after I had waited in line for 20 minutes and then, I couldn't get out of line to try it. I even talked to a CM at Sum and asked him if I could just get back in line if I ran over and tried the seat. He was fully capable of letting me out (I was at the front of the line at that point) and back in, but he wouldn't. So, just an FYI to look for the tester seat before getting in line.
Sum has a "tester seat" off to the side of the ride so you can see how the seat feels. Look for it. I didn't see it until after I had waited in line for 20 minutes and then, I couldn't get out of line to try it. I even talked to a CM at Sum and asked him if I could just get back in line if I ran over and tried the seat. He was fully capable of letting me out (I was at the front of the line at that point) and back in, but he wouldn't. So, just an FYI to look for the tester seat before getting in line.