May be I can try something different. For example, building a body using Lego. Previously I did build a Lego loco chassis but only thing I didn't like there is having to make use of plastic flanged wheels. I am interested in this chassis because it is very cheap and comes with metal wheels.
The kit locos made by IP engineering of similar manufacturers look very much toy like. Even Playmobil loco looks much better. I admit I never held IP Engineering locos in my hands - so my comment may be bit unfair.
Even though Roundhouse's Little John costs over £550, it still looks like a toy! If metal costs so much money, then they could always offer metal chassis and plastic body built on top of that.
As a contrast, track power locos (like LGB) look impressive!