John,
You didn't say if you use RAW. If you do, that would let out the G7, although it's sharp and has very good color. I actually preferred it over the G9. And, of course; both have that OVF issue.
The G11 & G12 went back to 10 MP, have good color, and a better grip than the G7/G9. In terms of what you shoot, the difference between them is that the G12 has a front wheel, and the G11 doesn't. In my hands, the front wheel affected the handling, so I preferred the G11.
I mentioned (I think) the G7 was a little sharper. To determine that, I downloaded the studio scene from Imaging Resource for each camera at several ISO settings, and then ran them through a good JPEG editor and added a little sharpening. The edited shots were then printed as borderless 8.5" x 11" prints. I then examined each print with a fairly strong magnifying glass that's normally used for thread counts in fabrics. With my reading glasses, I can't see any significant difference up to ISO 400 at normal viewing distances. I did run the G10 through that process as well.
I just took a break and went to my print files, and found ISO 100 and ISO 400 prints (as described above) for the G7, G9, G10, G11, and G15. I also found my thread count magnifier and examined all 5. As I said earlier, I really cannot see a difference with just my reading glasses, and I'm looking closely - like 6-8". The G15 is the exception, as Imaging Resource changed the lighting and the whole image just looks different. However, when I use the magnifier, I can see minor differences.
My advice would be to look for a really clean G11 or G12. Same lens as the G10. The G10 had over 14 MP, the G11 & 12 had 10. Even so, the extra resolution is eaten up by higher noise at ISO 400. And I don't see any better definition of fine detail; but I do see more noise grain. Also, the G11/G12 will do better at ISO 800. If I remember correctly, the G11/G12 had a fully articulated LCD; which is nice for sneaky shots with the camera at waist level. Normally, for cameras of that size, I use a neck cord attached to the right hand strap lug. Mainly because it wraps neatly around the camera and it's still able to fit in a loose pocket. With a 2 point attached neck strap, they don't wrap well and the whole thing isn't pocketable.
Hope this helps,
Jerry
Jerry