I Googled that and it gave me images of several very different train types - but some of them look promising. Combine elements of some of those designs (most-notably the single-width doors, rather than the space-wasting double doors seen on the UK FLIRTs) with the FLIRT UK nosecone design (I think the 745, 755, 756 and 231 all have the same shape cab/nose, correct me if I'm wrong) and make them as long as the platforms at Glasgow Queen Street (assuming this is the limiting factor) allow and you might be on to something - but need at least one full route with OHLE first.
The problem with Stadler is the wasted space from the power packs. A bi-modal MU with underfloor engines would be better in that regard. The engines can also be replaced in future with battery packs, hydrogen tanks, or whatever.
A big reason for using existing stock for the IC service was that the electrification plans were being thought of, and they didn't want to be stuck with unsuitable stock after the electrification strategy was finalised. Using existing stock, which has a shorter lifespan, sidesteps that issue
It is important to remember that the whole Inter7City network is suppose to be wired at some point (although no date has been given for most of Aberdeen-Inverness). Therefore, we shouldn't really be considering new diesel stock for I7C, it should be straight EMUs (or possibly rakes of coaches with driving trailers (similarly to TPE's mark 5s) with electric locos to push/pull them) which would mean no diesel engines to find space for. Unfortunately the current ScotRail HST stop-gap fleet is end-of-life in 2030, while wires are unlikely to have reached both Aberdeen and Inverness before 2035.
I would suggest a common base design regional/intercity (with single-width doors etc.) is used for the scenic routes and I7C with the regional version having fewer coaches (maybe 3 per unit), power pack modules for off-wire use and 385/377-style cabs for multiple working. The I7C units would be maybe 7 coaches long (one with a buffet counter perhaps) and would have pointy noses (UK-FLIRT style as noted above) and would not be planned for use in multiple. Given the later date of planned electrification between Aberdeen and Inverness and (I'm assuming) lower demand then Edinburgh/Glasgow workings I would suggest that the 'regional' units also be used between Aberdeen and Inverness, potentially allowing reduced weight once Aberdeen-Inverness gets wired by putting less fuel in and interworking Far North and Kyle diagrams with Aberdeen-Inverness so they have less off-wire mileage to burn fuel in each diagram.
Yes. The low-floor arrangement and gap fillers are unquestionably of huge value
Gap fillers yes - the only drawback to them I can see is delayed door release while the gap filler slides out - makes passengers on board wonder whether pressing the door button has actually worked. Low-floor arangements however are less clear cut - I would suggest the aim should be to get the floor level as close as possible to the UK standard platform height (915mm was it? I can't remember for sure) while still having a level floor inside including over the wheels/bogies.
Or passengers, if the interior of the 80x was to a decent standard, e.g. using the TfW seat cushion for Sophias or the alternative seat used by Lumo and Avanti. They're old and unreliable, and it shows.
I've not been on Lumo, but coming back from Scotland I had an Avanti Voyager from Glasgow to Carlisle (it was during engineering work so diverted), then a 397 (I think as far as Preston), then a refurbished Avanti Pendolino to Crewe and finally a TfW unit. Other than the TfW unit (I forget whether it was a 150 or a pair of 153s), the only one with decently padded seats was the Voyager. The seat used by Avanti was
not a noticeable improvent over the awful Sophias in the TPE unit in my opinion. I've only had a few minutes on the TfW version of the Sophias on the 197s (I've had just one 197 trip, which was Shrewsbury to Wem) so have not been able to give them a meaningful comparison to the Sophias on GWR and TPE but my first impression of the TfW Sophia is
not good and unlikely to be any different to GWR's.
However, that article is over two years old, and in the last 6-12 months it has become clear, as discussed in the appropriate threads, that the Scottish electrification programme is proceeding much more slowly than was originally planned and hoped, and is slowing down just when it needed to speed up, presumably because of the terrible financial situation of the UK generally and the Scottish government in particular. There has been a notable absence of visible progress on the acquisition of new trains - the most recent information we have is from over a year ago and was discussed at the start of a thread created then:
An advert for a tender for legal services for the above (https://www.publiccontractsscotland.gov.uk/search/show/search_view.aspx?ID=AUG455691) gives some more detail on the fleet plan ScotRail Trains (SRT) plans to replace 65% of its train fleet (around 675 carriages) in the period 2027 to...
www.railforums.co.uk
So it is not clear that your plan could succeed on the timescale you suggest.
The first review of the 2020 decarbonisation plan was originally due in spring 2023 and is now planned before the end of the year and referred to as a "refresh", so perhaps the situation will be clearer in 2 or 3 months, but not necessarily much brighter than it seems today.
Indeed, the suituation does not look good. It remains the case however that building new diesel trains now would give the Government a further excuse to delay much-needed electrification (and decarbonisation in general) because said new train would not reach end-of-life before 2060. It is my view that new bi-mode regional trains (something similar to a 158/159/442/444 with unit-end-gangways and a 100-110mph top speed) are a necessary evil because there are far too many trains in that category reaching end-of-life before we can get anywhere near enough wires up. However, with higher-speed (eg. 125mph) intercity (HST) stock we already have a large number of bi-mode 80x in existance (or on-order) and routes which have justfied investment in higher linespeeds should also be towards the front of the queue for electrification, so we shouldn't build any more and make do with what we have (though I guess ScotRail doesn't actually need the extra speed, so could use regional units you'd just be losing the nosecones and buffets in favour of end-gangways and multiple working of shorter units).