I think it's safe to assume the introduction of Class 150/153/156 is a good idea. A nice expansion for the GWR line. It's anothe DMU except more "square" like body. Pretty cool unit, i tried it out in TS2019 made by Armstrong Powerhouse and it's got nice features and that sweet rumbley diesel engine. I had alot of fun with this unit in TS2019, so in TSW would be truly epic.
What really intrests me about these is the fact that you can have only 1 unit doing a job. And normally 2 units are present.