Quote Originally Posted by Ollievision
Is a 2003 lens exactly the same spec etc as one that would be bought brand new today?

Older 100-400 units (before 2006 or so) had a reputation for a high percentage of "lemons" (some were soft at 400mm). If you get a normal unit, it will be just as sharp as one bought brand new today. Others have noticed improved bokeh in the newer units.