Plus the heartline(s) will be way out there. However as X is for real, this shouldn't be a big problem. I have thought a few times that they could add two more seats in the middle.
Funny, in '97 someone sent me their drawing of a new concept B&M train. He called it the "Hammerhead" & it looks exactly the same as a 4D train, only the seats are fixed & don't rotate. He even sent the drawings to B&M & they said it wouldn't work as there is too much inertia or something to do with having the mass off both sides of the track making it hard to yaw.
Coaster Bob, there have been several rumors years ago of the Arrow 64 Passenger Super Train. I wonder if there's any truth to it. My guess would be 16 rows of 4 or 8 of 8 (nah, that would look weird.)