I agree with this and the comments on the similar theme. I was in Cornwall in Mid January, funny enough on a 5 car, and Funny enough it was about 90% Full. Yes, the loadings will be spread out with further timetable improvements for the southwest, but a lot of these passengers weren't just local passengers. They had travelled for some distance, and it's easy to see why they are getting slated. They should have at least been more of a 60-70/40-30 split between 9 cars and 5 cars to the South West. You only have to speak to the staff, working these units day to day to understand that they are becoming nothing more than a disaster - I commute on them, and it's not easy to find a member of staff with a good word for them! Come to think of it, why cant the fleet be operated as 9 cars to Penzance, and the 5 cars on the shorter planned Exeter services possibly splitting there to allow 5 to Paignton and 5 to Plymouth?
A post above mentions the time it takes to split and join units - and potentially blocking platform space at Oxford. Yes, but these were ordered by the DfT who had a Bournemouth style of operation in mind. 10 car comes in, 5 car splits and heads off to their destination, 5 car heads off to the carriage sidings. All supposed to be fairly quickly operated. So I don't see why such operation, considered wonderful by the DfT and perfected by the Southern for Bournemouth, Couldn't also work at Oxford? Unless there are issues in the splitting of and setting up of the TMS's on each units that would really occupy the platforms space for that length of time? Yet it's considered perfectly acceptable for Plymouth which despite having more platforms than Oxford, is painted as somewhat of a rural backwater where their platform occupancy is significantly lower.