It somewhat challenges my initial perception that the 180 was nicer onboard because it had sacrificed seats for comfort.
The 180 is a far nicer train, full stop. Though Meridians are slightly less nasty than a Voyager. If you want to see an interesting article about train comfort, get the latest Modern Railways, where there is a huge table rating journeys on all kinds of trains - the 180 is up near the top of the league. Voyagers and Meridians right at the bottom along with Pacers. One of the reasons 180s have a decent number of seats by comparison with a Voyager, in particular, is that they don't have three disabled toilets per five-car train taking up vast amounts of floor space.
there were the same number of seats on a 5car Adelante as there are on a 3car turbo
Depends which variety of Turbo you mean Chris - there are 275 on a 165, more like 250 on a 166, due to the luggage spaces and 2+2 section with tables. A 180 has 284, though that I think includes the perch seats, so 270-odd proper seats on a 180. And these are seats you can sit comfortably in, as you well know Chris - quite unlike the 3+2s on a Turbo, which do not allow for the fact that human bodies have arms attached. And the Turbo seats are fitted right up against the bodyside, so you can't actually sit straight in the window seats anyway, even if the adjacent seat is unoccupied. Those seats were never intended for use on long-distance services.
FGW▸ 's accounts department may be touched by your concern for their track access payments. I would be rather more concerned about the groans and shrugs of resignation from passengers on Cotswold Line platforms when a Turbo hoves into view.
HSTs▸ and Adelantes don't produce either effect - why might that be? And as several posters here frequently suggest, there are people who won't go near the Cotswold Line because they might encounter a Turbo, which must be hurting FGW's bottom line.
If the Adelante fleet is going to end up on the Paddington-Oxford services the journey time is short
But it isn't on services out to Worcester, Malvern and Hereford, which is what these trains will actually be used for most of the time, so the old seats with new trim will do just fine thanks. And 2x180 still has more standard seats than a high-density HST, something like 440-450 v 400, which was why FGW used a pair of 180s from Oxford into London every weekday morning pretty much until the end of Adelante operations in 2009.
Insider, I think it's a safe bet that FGW will be getting all five sets in working order. Even when FGW only had three sets left on the books, there was a degree of rotation with the stored sets, which won't be an option in future.