Not wishing to perpetuate thread drift, but I don't quite understand what is the issue with doors at 1/3 and 2/3 the carriage length on the new 197s. From 1985 right up until ERTMS Class 150s were common on the line, including those which had been reseated with 3+2 airline seating for Centro services which as a one time regular user around the Midlands were a nightmare to use. Central even on occasions sent 170s up the line, lovely units with doors at 1/3 and 2/3, so it's not as if we've had the "luxury" of 158s for ever. Last time I went on a 158 from my local station (Fairbourne) to Birmingham the legroom was appalling and as bad as the 150s.
For long sections of the Cambrian, including here in Fairbourne, the train is the only all day and evening public transport available (my local buses finish at 2pm from Tywyn and 4pm from Dolgellau) and the train is actually very well used especially when TfW allow the use of Twirly bus passes on the services off peak. I've seen the length of time it takes to disgorge those alighting at Barmouth and Fairbourne even in the winter, and it is painfully slow, and the small vestibules are not very good for standing in for the six or seven minute trot across the Traphont. These new units will be welcomed by those who regularly use the trains especially those with mobility problems, of which there are many locally.