This may seem like a pretty straight forward question and the obvious answers are; amount of room, level of experience, rent or own, stationary or mobile. My question concerns the reliability of each scale. I am 86 and have been interested in model railroading since the early 50's with breaks for career reasons; but recently have gotten the bug again and started a model railroad in a 12' x 12' space. My hands are a bit shaky and my eyesight, good, but not perfect. At my age, you think you can do things like you used to do, but soon find out that is no longer the case. I can still get around pretty good, but crawling under a layout is not possible. I have had to work around layout building areas and try to invent new ways to achieve what would be easy 60 years ago. My first concern was how reliable are the different scales as far as power distribution, engine running goes. I started recently choosing Marklin HO because I thought it was very reliable running. To me there is nothing worse than having a train derail or quit running in a hidden area of the layout. I have been reading up on track cleaning and track geometry trying to discover the reliability I'm looking for. Marklin, I found is not as reliable as I first thought. I have a large amount of track already laid, but considering switching to 2- rail HO or even N. I haven't had much experience with N trains, and wonder, due to it's size if it is a reliable running system. I prefer HO because it is larger, but wonder about it's reliability over the long run. Bottom line is: I want a train that will run and run without a lot of fussing around like re-railing, looking for shorts, etc. I remember back in the 50's, model trains were not too reliable, but a lot has transpired since. Have the "bugs" that 50's trains had been resolved in the 20's? I am currently in the process of making catenary components that I want to install later.