ScotRail have used ironing boards in the 385s but with a differently shaped seat base cushion. The "default" cushion is quite thin and completely flat (i.e. perfectly horizontal). I don't mind it, but many people are not fans. The modified one is sloped slightly towards the seat back and slightly contoured, which does make a significant difference to comfort (I've tried both on adjacent seats during the ScotRail consultation). If they have chosen this one I think people will generally like it.
There's not a lot wrong with the *back* of ironing boards - some don't like them being upright but that's very much a "Marmite" thing, and they are quite thin-backed so will give good legroom[1] in all seats as they do on the newer Electrostars, while the high back means everyone can rest their head on them, and the tapering at the top means they are less claustrophobic than other very high-backed seats.
[1] If the number of seats per unit is fixed already, which I think it is, it is clear that thinner back = more legroom.