Deeply impressed by your analysis and line of questions, Tjm! I tend to read Wagner stories with an eye mostly to the surface level, because he's a world class entertainer. But I think you've hit on something not so far below the surface when you talk about us long-term readers being stand ins for both Winterton and Chopra, where we look back on what Dredd used to be like, is like now, and 'should' be in either time period.
There's another thread going about if Dredd is hero or villain and this story is a classic example of him being both, not least because we get to see two versions of Dredd behainvg slightly differently. 'Our' Dredd is heroic in the straight reading of the story,
where the clone was a Sov, Dredd intuited it, then it was confirmed moments before his accidental death. But he's also a villain because his treatment of the cadets and Cit-Def alike is SO very harsh we can't quite bear it - even if we might sneakily think that it's justified in a war setting.
And Dredd is arguably a villain even more clearly in how Winterton is treated. Whether Winterton's version of the story is true or not, they chose to lock him away for 40 years for spurious 'mustn't do anything to upset the power of the state' reasons.
But also there's nothing specific to this story that challenges Dredd's world as such, it's more of a ripping yarn with a reminder that the Judges like to control the narrative as much as any given Totalitarian state.