Back to topic, I've now been on one (Kings X to Donny this morning) and the verdict is that the seats (and everything else) are the same as the GWR newer moquette-covered type - OK, but not great - but what I would say is that the colour scheme makes it a much more pleasant environment - warm and welcoming rather than stark and like a 1990s bus. The GWR ones really would benefit from a good splash of British Racing Green inside.
I'd say overall it had the feel of a Class 444, which is overall a pretty good unit, though the seats were as you'd expect not as good as Grammer's offering. Ride slightly rough but nowhere near as bad as the awful Mk4 - does the ECML have particularly bad track, as it was rather better on the GW?
Used the buffet (due to a very tight connection thanks to LNR being unable to ensure traincrew for the 0715 off Bletchley - thanks guys, I could have had half an hour extra in bed), the coffee machine was broken but tea was Yorkshire so did the job. The range seemed VERY limited, though. It only seemed to take up about 2 bays, so GWR could easily retrofit without much seating lost.
FWIW I was surprised at how busy it was - is everyone off to Skeggy for the week or something? I had expected northbound at 0903 on a Sunday to be near empty.