I just purchased Magnum 15S transformer. I could not be happier. It now from my new vantage point seems very silly to skimp on a transformer. Kistbashing cars etc in order to have fun and save money sounds great and on my simple level I enjoy it but I cannot image trying to cut corners on a transformer. This thing has power to spare which may come in handy as the layout grows. In that sense to buy what you need now may prove more expensive as you move from one transformer to another as I have done. The Magnum supplied power on my layout on level track (over 75 feet of track) to seven lited passenger cars, 2 cabooses, GP-9, GP-38, 2 4-4-0s, 20 tonner, LGB 0-4-0 pulling 10 plus freight cars. The amps registered at 10.8 and remained there for a long run. I also found Dave Sauerwald at Bridgewerks very helpful and Bridgewerks site very helpful too.