Well, the registry of the Reliant
and TVH's Saratoga
are in the 1800s. All things being equal, if registries are sequential as one might think, this would mean they were built after the Enterprise
, although we do not concretely know this to be the case.
There's a fan design for a Surya
class "frigate" that is essentially a TOS version of the Miranda
, but nothing in canon to support it. It's entirely possible there was a TOS version, and we just never saw it; indeed, according to the "Court Martial" status chart there was at least one ship in the 1800s in service at the time of TOS, so it stands to reason the Reliant
Then again, who's to say the Miranda
class wasn't built as we saw the Reliant
, and wasn't the testbed for movie-era tech, before the Enterprise
refit was attempted?
I think the only conclusion we can concretely draw is that something about the Miranda
class (and Oberth
for that matter) ensured they were in service for around 75 years.
This would tend to make make one think there could have been refit Consitutions
in service too, even though we didn't see one outside Wolf 359 and DS9's "The Sound of Her Voice," both of which reused the TSFS wreckage. If the Excelsior
was meant to replace the Constitution
, then maybe something along the lines of Timo
's treaty stipulations made it advtangous to have an Excelsior
rather than a Constitution
: one big, more capable ship instead of one smaller, less capable ship. Further, the variants of the Miranda
seem to imply a modularity or versatility that we haven't seen in other classes to the same extent.