Modern Lionel bump and go trolleys have DC can motors and run much more smoothly and at lower speeds than the old #60 cars.
The only mechanical issues I've noticed are tracking problems through postwar O27 switches and crossings, owing to their lighter weight. For a simple oval or back-and-forth operation, they work fine!
Be sure to keep an eye on the third rail shoe, as it is prone to loading up with crud from the third rail.
Hope this helps!
Mitch