A newbies impression of the 109 and spit

[JtD]

Static stability is the aircrafts initial reaction to displacement.

Your words. It is my understanding that this is exactly what NACA assessed and what they found to be neutral or unstable, only that they used a different method for testing.
NACA didn't have a problem with (short period) oscillations over time, the Spitfire would dampen any (short period) oscillations within a cycle or two.
NACA did have a problem with the fact that a bit of extra elevator at any speed, if not reduced, would change the AoA for good, meaning the plane would not come back to a more level attitude even when speed was reduced.

Looking at the easy to understand diagrams CaptainDoggles linked, neutral static stability appears to be exactly the problem NACA had with the Spitfire.

I see you deleted your last post, but it might still help if I leave this one up to make sure we all use the same terminology.