Just as a matter of interest, were the Class 153 units intended for routes with loadings similar to those on the Borderlands Line?
153's were intended for rural line such as the borderlands line, ATW used them on the route but they lost time so much they eventually after years of unreliable services got replaced by 150's on the route.
The line has quite severe gradients that they struggled with & 153's have slow doors, there's 15 stops in each direction. The services got so unreliable the patronage dropped dramatically, most days at least 1 service would turn around at Dee marsh due to so much lost time.
This is big one concern I have with the 230's how reliable they are, the customers need a reliable service. The 150's are great on the route, since they got introduced patronage has risen.