I would be very interested in your opinion of the GX9 , when coming from a GF (GX800) camera.
It's a brick.
It feels a lot bigger and heavier than I expected, not helped by the camera search tool here getting it's weight wrong (it says 407g). It's 450g (with card and batteries), compared to 269g. It also feels bigger than I expected, it's about as big as my 35mm film SLR (which is 530g).
What probably doesn't help is it's very angular, it has square corners rather than the rounded ends of the GX850.
I prefer the twirly wheel on the back of the GX850 to the ones on the GX9. The GX9 has 2 knobs to twirl, which might be an advantage if I got used to it. They're a bit stiff so I found twirling one was moving the camera while on a tripod.
The lack of the knurling on the rear buttons (on the GX850 they're the twirly knob) meant I couldn't differentiate them by touch. I keep hitting one of the 4 buttons instead of the centre OK button.
Talking of tripods, the tripod mount is very far forward, there's nothing apart form the screw to stop the camera rocking forward, so if I didn't tighten the tripod screw with a tool, the camera would rock. All other cameras I get away with finger tight.
One amusing thing, the port cover is quite trick, and obviously very tricky. It comes with a little piece of paper explaining how to open it. I still couldn't open it. I consulted the manual, and still couldn't open it. It took a little more puzzling to work out what it's telling me. Once you know the secret it works quite well, but it obviously puzzles most of Panasonic's customers.
It doesn't have the two large handy function buttons on the top plate that I use a lot on the GX850. They're now small inconspicuous buttons on the back plate. One of them is the EVF/Monitor switch. Luckily the eye sensor is sensitive enough I don't think I need to use the EVF/Monitor button.
Amusingly the eye sensor is by default set to high sensitivity, if anything comes within 3 inches of it, the monitor will turn off. It took me a while to work out why the monitor kept flickering, my hand or arm passing by on the way to pressing a button was enough to set it off.
The EVF while nice does suffer from rainbow tearing for me. It may not be enough to dissuade me from using it, but could definitely be better. With my glasses on, I can't see all of the EVF screen at once, I have to move my eye around to see all the indicators.
I think the EV compensation dial is a waste of space, but that's mainly because I use manual most of the time and don't need to bother with it.
I'm really not impressed with the form factor, so I'm thinking of sending it back.
What is good about it is IBIS and BTLE, which is what I really wanted. I haven't had much chance to use the IBIS, but my initial impression is that it works very well, which makes my 20/1.7 much more useful. Most of my other lenses are themselves stabilized. This is the feature least likely to get on to a small camera.
I was particularly interested in the BTLE. This can supply GPS to the camera, and work as a simple remote release. Both of these work reasonably well, mainly dependent on the flakiness of the BTLE connection. I had the Image app crash on me and BlueTooth no longer worked until I turned it off an back on on my iPhone.
The BTLE successfully supplies GPS coordinates to the camera. It does take a few seconds after turn on for that to work. There's a GPS (BT) icon on screen to tell you it's working, though I'm not entirely sure it always worked as soon as the icon appeared.
The remote release is a screen on the Image app which just does the shutter, and nothing else, and works entirely over BTLE, so is not subject to the vagaries of the WiFi.
The good thing is there's no reason why a small camera should not get BTLE.
I'd also be interested in trying out wireless flash, but I haven't got that far yet. That's also a function it should be possible to put in a small camera.
There's a few other functions I discovered going through the menus, but I can't remember most of them currently. There's a highlight and shadows function which might be interesting, and is probably jpeg only.
I like the MyMenu, we could do with that on the GXxxx/GFx series.
It does have the C "Custom" setting on the mode dial. That's handy, on previous cameras I've set that up as a mode for my wife to use (who's initial is "C"). That's missing on the GX850.
I like that the screen flips down 45°, I've sometimes wanted that on the GX850. Flipping up 90° is probably OK, but I've gotten used to being about to flip the screen 180° and operate it from the front in some circumstances.
Edit to add:
I don't need the 20Mpix, I find the 16Mp is currently have quite sufficient. I definitely don't need 5.6MB jpegs and 24MB RAW files (compared to 4.4 and 20).
The faster mechanical shutter, with faster flash sync, on the GX9 is definitely something I'd like to have.