My experience with both Lionel and Atlas has been good. I have a Lionel TMCC Alco S2 and a pair of Legacy Fairbanks-Morse H16-44's. They run smoothly. The Alco engine sound on the switcher is actually that of a road engine, but it has a good high-pitched horn and will get down to a crawl. Having run it for years, it has needed no repairs. The H16-44's have really accurate F-M engine sounds with 8 throttle positions simulated. I rev up and idle down the engine sounds manually, and these two are terrific.
Atlas locomotives are bullet-proof. They will run for hours and hours at a train show. All of my 8 Atlas units are TMCC (only four throttle positions) with Engineer-on Board and so have lots of speed steps. The Mars light on my Atlas Erie-Built is a dual light that flashes alternately side to side, very realistic effect.
The Sunset units are the very smoothest runners I have, and use ERR with a later version of engine sounds that is more realistic. They use a very realistic simulated Mars light, and are well detailed and flawlessly accurate in paint.
