I'm afraid that's the most challenging, and expensive, section to electrify of the South Pennine route. (Batteries are probably ideal for the tunnels.) It's also a big part of the reasons for postponement/cancellation of the MML eletrification project.
Well per metre it is, yes.
But in the battery era I'm not sure how much cost per metre matters. I think the better metric is seconds of pantograph up per pound spent.
A kilometre of track on a 100mph railway only charges each train for something like 23 seconds. At 20mph it is 115 seconds, the 20mph section could be treble the price per metre and still be the better choice.
A station platform is great because it gets you the dwell time almost for free. The tracks around Sheffield are heavily utilised and at low speeds, especially between dore and Totley and meadowhall, I think they could be extremely expensive per metre and still be the best choice of charging location
Restoring at least a third track in from Dore and a total rebuild of the tracks through Sheffield won't be easy. Too much has been built on and around the old track layout quite apart from how the railway weaves around the Rivers Sheaf and Don and the industry that's been built around it and them.
Sensible, too difficult, leave it for another 10-20 years, whenever?
I personally think Sheffield needs a total rebuild more than anything, but I doubt one is forthcoming.
In the absence I'm not sure the BEMU programme can afford to get scope creeped into non charging infrastructure improvements.