allez donc voir ici

"As you can see any question that the EOS 30D is using a different sensor / image pipeline than the EOS 20D can be quickly quashed with a single glance at this virtual identical result."

Les courbes sont effectivement identiques ! Par contre le 30D ajoute des petits plus en rapidité à droite à gauche. Les plus importants étant l'ecran arrière et la mesure spot. Le reste, si on shoote en RAW, on s'en fiche un peu.

ET pour ceux qui se demandent si acheter un 20D est encore une bonne affaire:
"Overall Image Quality / Specifics
It won't come as much of a surprise if we were to say that we are just as impressed with the EOS 30D as we were with the EOS 20D, no surprise because they share the same sensor and image processing engine. Because of this then it's remarkable that eighteen months after the introduction of this sensor / image processing combination (in the EOS 20D) we've still not really seen any competition that can get close to this overall package of resolution, quality image development and low noise at high sensitivities."

En un mot, un 20D, cela le fait encore

A voir si le test dans CI corrobore celui-ci, mais cela serait surprenant qu'il soit différent.