I would suggest this unit for operations on the route from London Paddington to Hayes & Harlington. This and the class 800, as well as Heathrow Connect (maybe Tfl rail in a few years) and Heathrow Express trains would make Paddington look as busy as it is in reality. Obviously a version of this unit as detailed as the existing GWR class 166 would be really nice and highly appreciated. This especially if you consider that it could be used for many future routes as well (c2c, Govia Thameslink (and Great Northern), Gatwick Express etc.). I think a really nice feature for this train would be to be able to actually access the gangways and walk through the whole train if several units are coupled together. Selective door control allowing you to select which doors to shut off (usually carriage wise) for short platforms would also be very nice (yes I know this isn't an issue on the GWR mainline currently, but the feature exists in reality and would be a nice addition to the game, especially considering future route DLCs...).