Panasonic mixed the bodies from its Lumix and to design the GX9, and I've got mixed feelings about that. It seems to herald the merging of the two camera lines, which would make sense -- one's slightly lower-end than the other, but they're really not that much different. And while it retains the tilting electronic viewfinder, the best feature of the GX8, some of the other nice aspects of the GX8 have made way for some of the not-as-nice ones from the GX85.
The GX9 will be $1,000 for a kit with the 12-60mm f3.5-5.6 lens when it ships in March. (I don't have pricing for the UK or Australia, but that directly converts to roughly £720 and AU$1,270.) That's what the GX8 launched at for just the body, so the price has essentially dropped to where the GX85's was at its debut, and with a better kit lens.
On the inside, it has a new sensor which drops the blurring antialiasing filter (though it's the same resolution as before). It also has a new shutter mechanism with less vibration and has been brought up to date with all the latest Panasonic features. Plus, Bluetooth replaces NFC for connectivity, while the top keeps the more enthusiast-oriented control layout of the GX8.
The LCD has switched from articulated to tilting. Depending on your preferences, that could be a win or a lose. The fastest mechanical shutter speed drops from 1/8,000 second to 1/4,000, which probably won't make a difference to most people, unless they shoot fast-moving subjects.
But here are the serious losses: battery life and a decent grip. The GX85's body is smaller and lighter, with a flatter grip and a smaller battery -- 1,025 mAh vs. 1,200 mAh. So the rated battery life of 330 shots in the GX8, which isn't stellar to begin with, drops to 260 shots (using the LCD) or 250 shots (using the viewfinder) in the GX9. Sad.
Panasonic introduces a new Power Save LVF mode that it claims extends the battery life to 900 shots, but that's with the camera set to sleep after one second. That doesn't sound very usable to me.
To compensate for the flatter grip, Panasonic carved out a thumb rest on the back -- that helps, but if you're planning to use the heavier Leica lenses or shoot with gloves, you'll miss the more substantial grip of the GX8.
Or -- pet peeve alert -- you can buy the new accessory grip Panasonic's offering for it, which I believe will cost around $60 (equivalent to about £40 or AU$75).