I think even more stark than the scale change, is how much effort used to be put into the little styling touches on the 4-4-0 versus the cookie cutter industrialized modern diesels.
Oh wait, I was looking for Bernie's thread and somehow stumbled into Tom's... 
I posted this as part of my musings on how I was able to fit a O scale layout into my somewhat confined, narrow space. I only posted the comparison photo here, but more discussion was on my blog, including an early shot of my first layout in that room. That was an N Scale double-decker set in Utah in the 1990s. After several years, that layout is still alive in most of the benchwork in my current O scale layout.
The course of this discussion is a reflection of Tom's excellent modeling and the level of interest in modern subjects. Us odd balls doing the mid 19th century can only be regarded as mildly eccentric (OK, maybe not so mild).