I wish I could say I had the same success as Doug in the running department. I have video of the Lionel up f3's (pre legacy) that demonstrate smoother operation then my sunset f7's. With that said, neither set of engines or single engine for that matter has the slow speed smoothness of my Lionel s2. But that is not really an apples to apples comparison. I think the bottom line is now is if there is a big difference, than there is probably something wrong with the units your running.