Wikipedia may be out of date then - it said 272 (built with 316) for a 455 and 152 for a 456 That is 698 seats for a ten car train. I know they stripped loads out when the 455s went with the garish blue/pinky/purple interiors.
Wiki says 556 for a 10 car 701, or 538 for 2X5 car. That's a difference of 140... (allowing for some taken out of older units on refurb) hence I rounded down to 20%..... Hence, as ever, seating capacity will be down (SWT did this in the last franchise if I remember rightly, their bid said loads more seats, then said, ah, typo, we meant capacity, so they ripped seats out on refurbs... and customers just had to suck it up).
standing room isn't acceptable on longer journeys (by that I mean 10-15 minutes plus). Whatever the railways think - we will put up with in exceptional cases, because life happenz, but not every day, not for what is charged for tickets.....
these are so so intensively used an seating looks inadequate - ironically I am, as I write this, watching a 345 Cross Rail unit go past, the lack of seats is noticeable, it looks like a 1980's ) gauge model with no interior...
For what we pay, we expect to be able to sit. We expect a toilet. We expect AC that works in summer. We expect reliability. From the trains and infrastructure. We expect trains to actually run to the timetable (or publish an honest timetable). Oh, and not being gouged on insane car parking prices would help.