Hi, I just joined, and bought a Bachmann Niagara. My layout is not up yet, so I can just run it on my test track (Life-Like circle with 3 straights). I noticed two things with the engine. The pilot trucks hang up (18 inch radius) going from straight to curved. I filed the underside of the engine smooth just over the wheels, and that totally corrected the problem. The tender needs a lot of weight to track properly, but I haven't done that yet. Also the tender pulls on the back frame of the loco on curves which makes the front of the loco turn to the outside (contributing to the pilot trucks jumping the tracks). When I am up and running, I will experiment with a longer drawbar by moving the pivot point under the loco towards the front.
I had the same questions you did about the loco, which is one of the reasons I joined the forum.
Thanks