I'll give you the bottom line right now: It's a worthy upgrade and for reason's I didn't expect. I'll get a full comparison online at my blog in the next week or so. I need a few more days with the G11 and time to write it. Here are the highlights of what I've found (cliff notes version):

# ISO: G11 1-2 stops better. ISO 400 on G11 looks better than ISO 200 on G9. ISO 800 on G11 is perfectly useable up to at least 8x10" prints. My limit with the G9 was ISO 200. High ISO mode is somewhat useable up to ISO 12,800 if used carefully and within it's limits - acceptable for web use.
# AF: I'm not going to measure it to the 100th of second, but the G11 feels slightly faster, not worlds faster, just enough. The Servo AF actually works pretty well, G9 didn't have this feature.
# i-Contast: It actually works better than I expected. Very pleased. I will have images of this later. G9 did not have.
# LCD: increased resolution is welcome and noticeable to me. The swivel is nice, just like my Olympus E-3. Very handy with the G11, more so than on the E-3 (I just use it to protect the screen). LCD does not feel as robust as on the E-3, but that's the Oly pro-line DSLR, this too is acceptable for the G11.
# JPG engine: much improved to my eyes vs. the G9. Even at ISO 80, it is noticeable in blue skies with a much tighter grain in the G11 vs. the more blotchy grain in the G9. Tends to AWB towards a warmer saturation, very similar to Olympus.
# My initial shots with high contrast scenes are very good, the G11 seems to deal with highlight clipping much better than the G9 if both are set to an exp comp of -1/3 to -2/3. I leave it at -1/3 by default.
# The menu system of the G11 is nicer IMO, but it also feels slower than the G9.
# The larger wheel control on the back of the G9 is larger and feels better built than on the G11. This seems to have been sacrificed in exchange for the swivel LCD.
# Optical VF on the G11 has less pronounced parallax error than the G9, it is useable now - thank you.

Again, this is not a full review, just some notes from my first 3 days with the G11. So far, I am very impressed to say the least.

--
-Ken
'Don't feed the trolls!'
www.kwaphoto.com (images and photography blog)