I recall that they have larger fuel tanks as well?
And they should have proper catering facilities on-board, equivalent to the East Coast IEP fleet (IEP TTS Level 1).
There were mutterings (as there always are) about IEP also being fitted with larger fuel tanks for commonality, which would allow Agility Trains to hire them to FGW outside the IEP train provision agreement for additional services to the West Country.
It's all terribly complicated. Hitachi will be maintaining the AT300 sets for Eversholt/FGW, but as they're not on a pay per diagram basis, they risk IEP maintenance taking priority, so there needs to be a balancing mechanism which penalises Hitachi for non availability of AT300 sets and deals with the costs involved in hiring in IEP unit(s). This then gets more complex as Agility Trains will need to hire in AT300 units from FGW to provide IEP diagrams in the event an IEP set is unavailable.
I should retrain as a lawyer or one of those blokes who sells enormous adding machines, there's a killing to be made in the next 27.5 years with this farce.