I mainly meant economically and demographically (though places like Germany and Northern Gaul probably surpassed their Roman period peak a bit earlier) and not necessarily technologically.
And it's also close to 400-500 years since the real decline started in the 530-550s (plague, outfall of the Gothic wars and climate change intensifying). Or in the 3rd century which would make it closer to 800.
That's 600 years - even giving you that date, we agree!