The 600-610 both have a very nice sensor - I used one for 2 weeks last summer, I was shooting a horse event that the tight center cluster worked great for that but, i can see other applications where you would be doing a lot of focus recomposing. That is really my only complaint, and it isn't...
I've been doing a few more tests it higher ISO,
this one is at 25,600 with a +0.3 exposure compensation. The bokeh gets a little blotchy, but there is still plenty of detail in the main subject.
This is the St. Helena Cathedral in Helena MT. - I'm not really a religious person but the talent that went into designing and building of the old cathedrals makes me love to photograph them. Unbelievable really, and they didn't have CAD and powertools.
Here is one a bit before sunrise at ISO 9000, pretty impressive low light capabilities. I remember when the fastest film you could get was 3200 b&w, and it was super grainy...