They are far from perfect, in fact they don't even fall into the category of suitable for I7C runs - as both a stop gap and as a permanent solution. So much so, that ScotRail specified conditions for I7C stock specifically designed to rule out inadequate fleets such as the Voyagers. The franchise was more than just about replacing existing I7C stock with cascades; it was about significantly enhancing the offering on all fronts that passengers were accustomed to.
The Voyagers don't do this, but actually detriment this severley and provide a worse offering for passengers than a doubled 158. Their provisions would be an emphatic downgrade to what was proposed both with the introduction of HSTs (Abellio), and 'Hullinisation' of the 170 fleet (First) - to name a few proposed I7C pre-2035 proposals - let alone the pre HST I7C offering.
Additionally, the Scottish government have outlined plans to have all rail travel in Scotland carbon neutral by 2035, meaning any replacement rolling stock for the HSTs will most certainly not have diesel running in passenger operation.
There are a handful of routes you could put the Voyagers on where they'd be suitable. ScotRail I7C is certainly not on that list.
I feel that many don't understand the bigger picture when it comes to the Voyager fleet and I7C runs. There's much.. much.. much.. more to it than carriage numbers, ineffective tilt, maximum speed, and the provision of end doors.
There's no point in a five car fleet when there's a net decrease in standard seats than a double 158 due to severe space inefficieny. There's no point in a tilting fleet when the routes would need a multi-million pound upgrade to support it and when the benefits of tilt only produce a single digit decrease in minutes to journey time which could otherwise be achieved by acceleration. There's no point in a 125mph maximum speed for very much the same reason as the last one. And there's little point in end doors when they on their own right would be the only positive in a disasterous portfolio of downgraded facilities for passengers.
And that's even before luggage provisions, fuel emmissions, and what passengers were actually surveyed and found to want.
20 years ago, perhaps, but definitley not now.