The A4s, Kings and Britainias often seen (and loved) on preserved railways aren't branchline locos either and so are just as inaccurate as a J94/Austerity. How often did Bridgenorth see Kings? How often Rawtenstall a Princess?
True, industrial/freight 0-6-0s wouldn't have had much to do with passenger work but then I'm guessing many of the larger "freight only" locos didn't spend much time on carriages in pre BR and BR days but do now in preservation.
What's more fun, a 4-6-2 barely making any effort with 6 Mk1 coaches trundling along at 20mph or a J94 actually putting some hard work in on the same load?
Give me the smaller locos any day!
Happy modelling.
Steven B.