I have the G9 and G11, and prefer the G11. I use the swivel LCD all the time. If you use the G9 more as an RF style camera, then the swivel LCD may not be a factor. The G11/G12 have essentially the same image quality at all ISOs, and can give you better results up to ISO 3200 than the G9 is able to do. I just compared side-by-side images of the G9 and G12 on the I-R Comparometer, and they seem pretty close with the G9 at ISO 400 and the G12 at ISO 800, so looks like a one stop difference.
http://www.imaging-resource.com/IMCOMP/COMPS01.HTM
The G9 lens can take you to 210mm equiv., while the G12 is limited to 140mme. That may also be a factor for you. It took me a while to get used to the loss in zoom range, but I can live with it.
The latest chatter is about the new G1 X due out soon. The large image sensor will substantially improve DR and high ISO results, but sounds like it will perform comparably to the G12 shutter lag, etc. And, of course it will cost twice as much. Since you already have DSLRs, you may not be concerned about quick performance, but would like DSLR image quality. Something to consider.
My guess would be you would miss the G9 RF qualities. The G9 also handles well when compared to my G11, with less accidental activation of the Menu button, and others on the back side. You might be interested in getting one G1 X, and keeping your G9s?
Dennis