Ive seen some 153s banging up together to for 2 cars, such as one consist with a 150 + 153 + 153 or 153 + 153..thats FGW bricks mind.
They also seem to take forever and a day to take off, and when they do theres no stopping them!
The original Wessex seats were comfy, but had a job to look out the window unless you are 7ft tall, thankfully this is problem is eliminated in the Richmond seated refurb bricks.
There was once when a I got on a super packed RR Class 153 in wessex days from Bath to Trowbridge (being an ex-CT 153 IIRC) and was so packed most people were standing in the back cab, jammy sods!
Cheers,
James.