I was intrigued with this mode ever since Panasonic announced it.
When I received the review G9 from Panasonic New Zealand, I spend nearly three days (out of the seven given days) experimenting with this mode.
As a matter of fact, if I would plonk down NZ$4,099 for this camera (with the kit lens), the Hi-Res Mode is a deciding factor.
What is this Hi-Res Mode then?
Basically, when you set the G9 in this mode it will take 8 similar pictures in quick successions, each exposure will have a HALF A PIXEL SHIFT, the camera will then combine the eight shots into a whopping 80MP Hi-Res file.
The Hi-Res image measures 10368×7776 pixels, and will print to 35x26in using the photo-quality 300 ppi print standard.
To get more information on this mode, I suggest you visit this Panasonic UK site.