Performance is not great and congestion is often cited. It also takes a long time to recover from any delays despite over £1bn spent around Reading and Hayes trying to relieve it. The difficulties around splitting and joining as well as doubling up on crew don't make it worth it.
You lose almost 20% of your Standard Class seats by running as 2x5 than 1x10 that means per seat the train is 20% more expensive.
You aren't ordering 700 seats on the "off chance" just spend a few minutes at Reading in the rush hour.
I don't know why you try to be so patronising when everyone can see the industry has got this wrong so many times before.
Also to mention I feel there should be a greater 9 car IEP ratio. There will be on the East Coast. Why are 2/3rds on the GWR 5 car on both 8008`s and 802`s and as you say what a waste of room with 2 unused kitchens at weekends on a 2x5 800. It seems most services are going to be 2x5 anyway so how can this be less economical given that 10 coaches have 6 engines as opposed to 5 on a 9. Surely make more sense. Still, what do I know?