...To be sure, Janeway's crew might have been truly ignorant of the shortcomings in "Caretaker", as the ship apparently was summoned to her first mission without much prior testing. Stadi would be speaking out of manuals, not out of experience, when bragging to Paris. For all we know, even the Intrepid
herself had not yet finished testing the edges of the envelope at that time.
It's only the repeating of the 9.975 specs well into the adventures that creates an annoyance here. Otherwise, we could take "Threshold" at face value (now there's an idea!) and decide that the ship's performance was reduced early on, and possibly kept on degrading. But it's pretty darn difficult to wiggle out of that repeating of the figure, unless we indeed think the crew feared a Starfleet politruk would overhear them and force them into the "Rascals" cloud to relive their youth or otherwise torture them.