A couple of weeks ago, I had to to Edinburgh-Aberdeen on a 158. Anyone who says they like them must be mad! Three hours jammed into a hard Richmond seat that seemed to be tipping forwards the whole time as if it wanted to shoot me onto the floor and with a headrest that pushed my head forwards so that my chin was jammed into my chest. Then there was the noise, there's something malevolent about the 158 when starting. The ride was OK at 70-90, so I'll give them that. Still, next time I'll get into the 170 instead (only went to the front to save on walking at the other end).
There happened to be a 156 in the next platform. Softer seats without those awful headrests and a much nicer noise. Also probably a better ride at 50-60 (West Highland/Far North sort of speeds). Only BREL could have ruined such a great design by trying to make it go faster.