Talking about my own experience... in relation to Toad comment...
I don't think I need more of what my 5D gives me... I really don't need anything bigger or faster... but I don't think I will be happy with anything a bit less... specially in action and macro photography... I use prety much everything my camera has, because to be a pro DSLR I consider it very austere...
I was working with a 350 and my lenses for a period of time and my pictures are really beautiful, I think if I post two pictures it would be very difficult to see which picture comes from which camera... but then for bird shooting it is slow and the small viewfinder doesn't help much...
I keep trying my best with the G9 and there are crucial things that limit my work like noise and chromatic aberation... only those two things really hurt the quality of my work... maybe I still need to learn a lot more about noise reduction... and how to cope with CA... so far.... yes I get nice pictures from my G9 but there has to be certain light conditions for me to get what I really like... the thing I love with this camera is to be
unintrusive... people don't feel threatened by a small camera ....
But you may ask why I started taking pictures with a G9...
Luminous Ladscape challenged a group of photographers with a series of pictures of the same landscape, one was taken with a G10 and the other one with a Hasselblad... it was a difficult for those experienced photographers to make a difference...
The review is titled
You've got to be kidding!
At the end of the day, your photograph (I am thinking about a printed image)
will be a success or not by itself, regardless the camera it was taken... I tell to myself...