I just parallel tested my beloved G9 vs. my new G10 using a tripod; same subject, lighting, settings, modes, at ISO 80, 200, and 400. The 10 renders noticeably crisper and cleaner pics than my 9. Also, my G9 consistently produced images that were 10 to 15% on the dark side. The 10's exposures are spot on. I no longer have to jiggle with in-camera exposure comp for each image or take each one to Photoshop for correction. And I like the G10's much improved LCD, the wider angle lens, and better grip. I think you'd like the 10. I couldn't be happier with my purchase.
I would love to know any comparisons of the G9 vs the G10 in shooting live concerts. I use my G9 for small club gigs as well as big rock concerts and while it's ok, there is a lot of noise in low-light situations requiring high ISO. But, I am concerned that the zoom not being as good on the G10 would make it moot. You can see some sample pictures on my site http://www.guitarvibe.com