NACA did not classify the Spitfire as Unacceptable what it actually said was .."therefore failed to meet the accepted requirements" (NACA's referenced requirements ... nobody else's) and to a specific item. If you read the various NACA reports in their entirety you don't come away with the impression that the Spitfire was a POS from a handling point of view.
They also said with respect to being able to rapidly pull to Clmax without the risk of stalling:
Something most Fighter pilots would consider a highly desirable characteristic.
CRUMPP you said above:
"As for the original premise of this discussion, the effect of a hard buffet for stall warning on turn performance:"
The premise of the discussion was NOT flying in Hard Buffet at all ! but on the very first indication i.e. The "Buzz" or the "Nibble" or the "Burble" ... what ever you want to call it. In a previous post you erroneously said the Buzz and Buffet I described was in fact the stickshaker going off even though in these aeroplanes no stickshaker system was fitted, you also told me that it was only valid technique in FBW aircraft ... even though we were talking about coventional cable/pushrod flight control systems ! You fail to accept that flying on the Buzz was/is a technique practised by Fighter pilots the world over and examples provided in this thread from at my count by 4 independent people/references ... by those that have actually used the technique....including a Spitfire pilot from the Battle Of Britain.