We're doing experiences with long-distance 350s are we? Well, I haven't had the Transpennine experience yet, but I travel with LondonMidland from Crewe to Euston every couple of months and it's great! I honestly don't mind the longer journey time if it's more comfortable. It's not just the seats, the air conditioning in 350s seem to cope much better in the heat than the 390s, something I've been enjoying lately. It's also in this weather when upgrading to first class has the added benefit of being enclosed on both sides with no external doors (admittedly, you get this as standard on Virgin, but last time I upgraded to first class with LM, it was still cheaper than standard on Virgin). I can understand disliking them if you had to take the long journey frequently though. You'd probably want that extra time either in-bed or partying or whatever.
In regards to on-board shops, I can't say I buy much from them when I'm on a Virgin as I like to buy a bunch from the station (Bite Card holders represent!!) but I agree having the option is nice. However, as mentioned in the thread already, the LM services are several stopping services attached together. People will more likely be traveling shorter distances and won't *need* to buy stuff on-board, compared to those where there's often an hour or so between stops. Alternatively, why aren't there vending machines on trains any more? Do they cost more to maintain than having trolleys or shops, or is there another reason?