As someone who worked the Euston - Birmingham and Birmingham - Liverpool routes on 350's, can I point out the following...
Most passengers travelling end to end on the Eustons didn't give a tuppence what train turned up as they were far more interested in the fact they had a one way ticket for £6 (£3.95 with RC), an open return for £23 or a Groupsave on London Travelcards, none of which Beardy was offering. They all bring their own refreshments or dive off at Northampton for the layover.
The only complaints I ever used to get about the 350's, whichever mark, were about toilets being unavailable/flooded, air con being too cold (particularly in First),lack of luggage provision and sockets. Never once did anybody moan about 3+2 seating. Indeed many passengers liked the 3+2 as they used the '3' seats as a bed!
And of course the people that had been silly enough to pay for First. They didn't tend to be too happy.
Personally I have never understood the obsession with Pendelinos. I find them exceptionally cramped and uncomfortable with hard, bolt upright seating and no aisle space whatsoever. I avoid them and Voyagers at all cost and am happy to accept a change somewhere if it means keeping away from them.
At the end of the day a single 350/2 would be a suitable replacement for a 304 for on the Liverpool to Crewe service in this day and age. Two 350/2's per hour stopping at a large number of shacks is not a suitable replacement for a stopper to Crewe and a Fast beyond. Not allowing for the growth in passengers.