i mainly want to use locomotives that were used in the 1950's, but i want to buy engines from different eras as i am not a prototypical kind of guy, i want to make a layout that could represent different time periods therefore i could use everything from tiny 4-4-0s to ES44ACs. some people might not agree with that but one guy in my hobby shop said no one should tell me how to use my layout. i agree with that, i am not saying anyone is trying to do that but it would be slightly annoying. of course i won't run 4-4-0s with gevos. but i will still collect them both. at the end of the day i just enjoy my hobby and that's all that matters.