Their heaviness is what turned me on to them because when I re-do my layout, there will be grades and I would like a single steam locomotive to pull a 20 car train unassisted. Also it seems there is a vast supply of parts for when something does break. I will def have to contact yardbird (I have been looking at what they offer) but I think the hardest thing for me right now is time, as I'm a full time college student and working full time; essentially a major layout upgrade is waiting and I barely have time to work and hone the modeling side. I wonder how hard it'll be to add a decoder and all wheel pickup...