90's have been used on the ECML London - Leeds jobs before without any problems. Their faster acceleration does indeed allow them to keep time on those services with more frequent stops.
Did, NR claim it's now a 125mph railway so I don't think it's as clear cut as it was back in the late 90s. Also don't forget that GNER chose to spend half a million quid on the 89 rather than hire a 90, it was cheaper to do that during the 91 HGR programme. My experience of the skodas back then was late arrival most of the time, I used EC frequently between Stevenage and Donny en route to Sheffield.
There's a reason why VT went to FL for their pretendalino 90. This, if it happens, will be a farce. There's no way DBS will spend significant cash on any of the 90s, it simply won't pay to do so.
If they are looking for another set, there aren't exactly a pile of Mk3 DVTs ready for use. If the skodas are for use with Mk4s they'll need working UIC connectors and rubbing plates.