Amusing to compare the "nobody will notice the change from a DMU to an EMU' argument when I'm so used to hearing the "bi-mode will be so noisy that passengers won't be able to hear themselves think with a diesel engine underneath the floor" line of argument...
I think the point was that electrification is not a massive improvement compared to making the service quicker/more frequent/go somewhere useful
Marginally faster (due to improved acceleration/ deceleration/ generally shorter dwell times).
But the main improvement is longer trains/ more seats on the electrified routes which means cascaded DMUs that will allow longer trains/ more seats on the routes that aren't currently being electrified (Warrington Central, Calder Valley etc).
It's not cost effective to build new DMUs at the moment, so electrification is the best means to an end (of longer trains, extra capacity).
More capacity. If you can get a seat, the train is *much* more attractive.
Yes, that could be achieved using DMUs, but there aren't any
That's it, in a nutshell.
To achieve growth though you need to attract people who don't currently use the train. Unless they've tried before and been put off by overcrowding, they won't have a clue how likely they are to get a seat. Unless there's an obvious improvement in the timetable, which isn't planned AFAIK, any increase in passenger numbers will be dependent on getting maximum publicity for the 'new' trains. Does the expiring franchise have any requirement to or interest in advertising the new trains?
We've seen pretty significant passenger growth over the past generation, even on lines that have seen practically now improvement in timetable or in rolling stock (or advertising).
One thing I miss since privatisation are days like Network South east used to do which is go anywhere on the Network South East network for a £5. I do not see any of the private railway companies doing that
Erm, LM Great Escape? Though there's not been one for a while, it might have become the victim of its own success
Northern do "ten pound" day tickets, EMT do "Red Dot" days, Southern do something similar, there's Club 55 at ATW/ ScotRail etc... plenty of offers from private TOCs.
However, with the railway a lot busier than in Network South East days, maybe they think there's less need to do this kind of thing (back then, Sunday was a quiet day, now it's a major shopping day with regular sporting fixtures etc too - so trains aren't so empty).
New branding - "Northern Electrics".
I like it - smart.
I think for the passengers of other lines to want their line to see the same treatment they really need to introduce frequency enhancements or improved connectivity.
I'm sure passengers using the Ormskirk-Preston service would love to get a half-hourly to Liverpool but I'm not sure they'd be excited about the prospect of the existing Ormskirk-Preston service being operated by a 319.
There's more chance of getting that half hourly frequency if we can displace dozens of DMUs from other lines (by electrifying them) to potentially cascade onto other lines (like to Ormskirk).
Exactly why would using a 319 increase alone increase patronage over running a 4 car Sprinter formation? It wouldn't. The public don't share the view of some enthusiasts that electric trains are paradise on wheels.
Where's the spare DMUs to allow four car operation on all line like this? There are none. So, if you want four car operation, electrification is the best option.
Debating 150 vs 319 on a route not on anybody's electrification short list?
I think there are more urgent matters.

A 4-car EMU beats a 2-car DMU any day of the week on any of Northern's routes.
The fine tuning can come later.
Well put!
Enthusiasts are far too obsessed with the "fine tuning" and generally fail to see the bigger picture.
I remember the days when 319/0's used to work to Rugby in Connex days. I would prefer them any day over a 150/153/Pacer etc...
Why all the fuss !?
Why the fuss? Because people like to complain, so that they'll even complain about increases in capacity, better trains, investment... because it won't be brand new trains.
Daft, I know, but people want to find something they can moan about (and ignore the bigger picture)