Most of what I run is scale locs. I notice that with all the sounds and the scale size, the locs look best when running slow. On occasion, I will crank up the speed but most of the time I like the look when they run slow. It seems to imply a heavy load is being pulled. In contrast, when I run my old post war stuff and my LTI non-tmcc engines, I tend to run them much faster. I don't enjoy the older locs running slow. It seems I enjoy them cranked on the layout. I think its because the older stuff doesn't seem to invoke that heavy freight load being pulled as the newer scaled stuff does.
How fast do you run'em?