The only rough train is 5. I've ridden every single train on the coaster, and 5 was the only one that I would consider being near rough at all. And too be honest it wasn't that bad. It was comparable to an older wooden coaster, that has had fairly good upkeep over the years.
Some people have to drive over ten miles, or jump on a plane to ride high class coasters worst than Rockit, and you guys complain about it having a rough train