There is a limit to what I can contribute to this subject simply because I simply can't give any credibility to later contemporary sources regarding the subject. In my opinion by that time they were just way too off-base. If I were to sit down to seriously design the Valiant I'd ignore pretty much most everything that followed, especially FC and ENT.
Oh, I'd say the contradictions and discontinuity are there, and they do tend to rear their ugly heads from time to time, much to our annoyance , but TOS had contradictions aplenty within itself and I'm always pleasantly surprised when Berman & Co. did manage to get something right.