"My evidence is the damned original Writer's Guide which is supported by a spoken reference onscreen. That's worth a helluva lot more than your opinion. And the Writer's Guide is Gene Roddenberry's intent which also carries more weight than your opinion. And I reiterate that these two bits of evidence were never contradicted at any time later."
Exactly. During the original run of the first season fans may have speculated what Dehner's comment was supposed to mean. The Making of
Trek and/or the original Writer's Guide
is in essence the late, but official explanation from the creators (Gene Roddenberry and Bob Justman) that Dehner refers to a "destroyer class" vessel (and not one of the "starship class"), Kirk's first command.
As this has never been contradicted later, we should respect the creators' original visions, IMHO.