Except the refit isnt canon. The canon Post-Nemesis Sovereign (as far as we know right now) is identical to the Sovereign depicted in Nemesis... and that is the Sovereign on which I based my specs. Realistically... the Sovereigns overall dimensions (width, beam and length-wise) did not likely change, but Nemesis establishes that the Sovereign-class has 29 decks in some fashion, and those are the specs I used.
So when I say Post-Nemesis Sovereign... I dont mean the refit that John Eaves had planned if the Big-E got to fly again, I mean the Sovereign as it existed in Nemesis and after as we know it. And the one in game does appear to be the Nemesis Sovereign.
Off topic here: The sovereign in sto is no where near the nemesis E as seen in the movie. Its more First Contact/Insurrection sovereign class. Yes the nemesis had is dimension changed among other things. Its shorter then the original but taller to plus the add decks up to 29 or they could have changed the numbering system. And yes we would have been treated to the full complete refit of the Big E but due to budget cuts it never made it but pictures on the net exist.
Back to topic: from what I have seen with my own eyes is that the regent looks shorter than the sovereign class but has a wider saucer and seems to be a bit longer too.