Why do so many people want to cut back on Manchester's cross-country services (which are presumably provided because a market is believed to exist) and degrade the quality of the Manchester-Birmingham substitute? A 350 with its large two-thirds doors and three small saloons per vehicle can never provide a proper inter-city environment (just as the 185s don't).
My reasons:
1. We don't have enough stock to meet current XC demand (need trains capable of meeting current Voyager paths - with their fast acceleration etc - hence the of-discussed idea of eight coach HSTs being a non-starter)
2. We look like we are going to have a surplus of 110mph-capable DMUs (350s, 360s and/or 379s) due to brand new stock in the south east
3. We currently need seven (?) Voyagers to run the half hourly Birmingham - Manchester service
4. Liverpool - Birmingham is run by 350s every half hour
5. Something similar to the 350s has been used on services between Liverpool/ Manchester/ Leeds/ York for a number of years now
6. New Street has a terrible problem with air pollution
7. You could run an eight coach EMU on services from Birmingham to Liverpool and Manchester - with 2+2 seats - that'd free up a number of Voyagers (which are required on the remaining bits of the XC "core") and give Liverpool/ Manchester passengers a better chance of a seat (as well as soaking up more of the Wolverhampton traffic than a Voyager currently can)
8. Controversial idea, but how about giving the WCML franchise the responsibility for Birmingham to Liverpool and Manchester and giving the Birmingham - Oxford - Reading - Southampton - Bournemouth service to GWR (i.e. allowing XC to concentrate on the North East - South West corridor)? That'd mean giving GWR around a dozen Voyagers (puts down his crayon)
Downsides:
1. Platform capacity at New Street. No getting away from it (and I'm not naively hoping that punting everything along the line to terminate at International will be a "magic bullet" to get round things). Interworking the Liverpool and Manchester services at New Street may improve things, but I accept that infrastructure may be the sticking point
2. Through trains from Manchester to Bristol etc. For a while under VTXC there were no services from Manchester to the West Country (there was 3tp2h to the South West from the Yorkshire corridor and a bi-hourly service to the South West from Scotland down the WCML avoiding Manchester). Are the number of people doing through journeys of hundreds of miles worth inconveniencing passengers on the Manchester - Stoke - Wolves - Birmingham corridor?
3. First Class wouldn't be as nice on an EMU like a 350. Maybe not - though I'm guessing a Voyager isn't exactly amazing in FC? But, again, needs of the many and all that. But with modern eight coach EMUs available, you could tart them up quite nicely. There's only around five intermediate stops from Birmingham to Manchester (e.g. Wolves, Stafford, Stoke, Macclesfield, Stockport), so not like the First Class passengers will be inconvenienced by doors opening every five minutes (since I appreciate that some people get quite sniffy about having their journey disrupted by doors opening).
I'm not saying it's perfect, just that it's better than the status-quo (whilst we wait for HS2 to finally arrive).