Much, Much better in 480p on a PJ than via RGB. Looks pretty much as good as the PS2 version on 480p where as the RGB image is pretty rubbish compared. The picture is much sharper & the colours are more vibrant (but not in a bad way).
Its good in progressive, only problem is that it doesn't fit the screen properly on my 32" CRT, but other than that is the image is much better than with RGB scart.