There are some that are in theory the right length and have had doubled up formations stopping there for years, but now the unions have decided they're too short in case the driver pulls 5m too far forward or stops 5m too far back.
Platform length make-up is written in a RSSB standard and the unions have no grounds for complaint if a platform meets this standard. What you may be referring to is a 2x150 formation being permitted but a 2x156 formation being too long owing to the extra 6m of length, as occurs on the Knutsford line. In this case one unit may be locked out, or detached if appropriate to be used for another service/left in a platform all day.
I suspect the bi mode portion of the contract will be used more heavily on the Yorkshire side
The west side is better suited to trains with 25kV + short-range battery whereas the east is better suited to 25kV + long-range battery units, where charging can only really be done at electrified termini stations (Leeds, Newcastle, Darlington, Sheffield*, Carlisle).
One does wonder if there would be 3rd rail charging capability at Southport, or 1500V at Sunderland.
Based on the incomplete OLE make-up of the routes these trains will be operating, with multiple power changes during one journey, if I was a business development bod at a company specialising in APCO (automatic power changeover) balises I would be investing heavily in my relationship with NR right now. Going to be needed at...
West side: Hazel Grove, Bolton, Trafford Park, Hunts Cross, Stockport, Oxenholme, Carnforth, Ashburys, Salford Crescent, Kirkham, Manchester Victoria, Warrington BQ, Preston (Farington Curve).
East side: Skipton, Moorthorpe, Newcastle, Darlington, York, Doncaster, Leeds, Carlisle, Doncaster.
Not to mention all the future electrification limits such as Heaton Lodge, Deighton, Bradford Interchange, Micklefield, Sheffield, Chesterfield, Wigan Station/Crow Nest Jn.