Specifically, I saw images at www.pbase.com/janus (which was listed as a reference in one of the reviews of this camera in the 'reviews' section of this website) and page 19 of the April edition of the magazine Shutterbug. It's a giant eyeball, and the lashes are so detailed they are frightening.

As to your other questions, the largest size a client has ever ordered from me is 16x20. Typically, though, clients order 5x7-11x14. Pretty standard stuff, but I couldn't stand the results with my Canon EOS 35mm. Not nearly sharp enough.

I think it would be helpful to compare, and yes, I have several good labs in my area (near Philadelphia). I'll see what I can get from Sigma, and maybe Canon, Nikon, and Kodak as well. I would really rather try them all out, doing what I do, though, as samples of landscapes don't help me too terribly much.
Thanks for your help,
Carolyn