Quote Originally Posted by mhhenn View Post
but when comparing the jpg images that both produced I have the impression that the 550D delivers a better image.
First of all, welcome to the forum.
I shoot with a 1DmkIIn and a 5D.
If you examine your images I think you will find the 550D is sharper due to the higher pixel count but the 1D will have lower noise at higher ISO, better contrast, better color, etc... Bottom line they all return great IQ. I love my 1DmkIIn. I do not think I would like a 7D or 70D but I do find myself wanting more pixels