I personally believe that my body type greatly influences how rough I perceive a ride to be, since I am 5'11", 135 pounds - so I have a lot of wiggle room within restraints to be rattled around. For instance, I found Fury 325 to be slightly rough, when many others didn't.
Yes, that could be. For example, I love Skyrush, but I do find the restraints uncomfortable. But I like Verbolten's trains and find them very comfortable.