The SOTS version of the Constitution II/Enterprise II are variants of the TMP design, but only constitute a small number of builds or refits. For my part, I treat them as basically being variants of the Enterprise class and not so much a separate subclass. That series also has the Miranda type builds as being direct evolutions of the Coventry/Surya designs, which are essentially TOS type Mirandas with no rollbar (an addition unique to the later Avenger/Miranda model).
I also like the idea that designations like Miranda and Oberth could refer specifically to models in service in TNG, and thus not necessarily conflict with class names in sources like FASA and SOTS (for headcanon anyway). FASA had several variations of the Oberth family that outwardly looked identical and only had different internal variations, with the Tsiokolvsky being a Sagan class refit (which was intended to modernize the design for the TNG era but only a small number were apparently built). Starfleet would have also been working on prototypes for vessels like the Nova class at this point, so I can see fewer refits occurring. Especially adding in the Jackill's subclasses as well, which mean that Starfleet had gotten a lot of good use out of the design.
I use a similar headcanon system to reconcile the canon Ambassador with the one FASA created for the TNG Officer's Manual, which is entirely different (based on dialogue from "Conspiracy"). The FASA Ambassador seems like a curious hybrid of Excelsior and Constitution/Enterprise elements, and was apparently designed to fill the heavy cruiser with a much more powerful armament (lots of phasers and 15 torpedo tubes) due to tensions at the time with both the Klingons and the Romulans. The Excelsiors were considered battleships in the FASA continuity.
Only 15 vessels were built and several of those had been lost in the line of duty by TNG season 1, so I like the idea that this Ambassador simply didn't work out as it was initially planned. It was overgunned and likely expensive to produce relative to its utility, in an era where the Klingons were becoming an ally (and actually Federation members, if one takes the OM's approach
) and the Romulans had gone into isolation for decades. Perhaps some of them fought in the Cardassian wars of the 2350s and were lost or damaged that way.
So the canon Ambassador class (which in this context I call the Ambassador II), as we see in TNG, was selected as an alternative design concept that more accurately kept the traditional cruiser balance of systems and could also employ more advanced systems than those used to build the Ambassador Is. Those Ambassadors were eventually retired from service and the Ambassador IIs had a longer service life.
Headcanon is so fun...
I also like the idea that designations like Miranda and Oberth could refer specifically to models in service in TNG, and thus not necessarily conflict with class names in sources like FASA and SOTS (for headcanon anyway). FASA had several variations of the Oberth family that outwardly looked identical and only had different internal variations, with the Tsiokolvsky being a Sagan class refit (which was intended to modernize the design for the TNG era but only a small number were apparently built). Starfleet would have also been working on prototypes for vessels like the Nova class at this point, so I can see fewer refits occurring. Especially adding in the Jackill's subclasses as well, which mean that Starfleet had gotten a lot of good use out of the design.
I use a similar headcanon system to reconcile the canon Ambassador with the one FASA created for the TNG Officer's Manual, which is entirely different (based on dialogue from "Conspiracy"). The FASA Ambassador seems like a curious hybrid of Excelsior and Constitution/Enterprise elements, and was apparently designed to fill the heavy cruiser with a much more powerful armament (lots of phasers and 15 torpedo tubes) due to tensions at the time with both the Klingons and the Romulans. The Excelsiors were considered battleships in the FASA continuity.
Only 15 vessels were built and several of those had been lost in the line of duty by TNG season 1, so I like the idea that this Ambassador simply didn't work out as it was initially planned. It was overgunned and likely expensive to produce relative to its utility, in an era where the Klingons were becoming an ally (and actually Federation members, if one takes the OM's approach

So the canon Ambassador class (which in this context I call the Ambassador II), as we see in TNG, was selected as an alternative design concept that more accurately kept the traditional cruiser balance of systems and could also employ more advanced systems than those used to build the Ambassador Is. Those Ambassadors were eventually retired from service and the Ambassador IIs had a longer service life.
Headcanon is so fun...
