Well, g9/gh5 will give a bit more and the em1 ii in terms of af/performance.
The GX9s AF was more than good enough for my use.
Good camera and system, but wasn't happy with the IQ at ISO 3200 and 6400. So a switch from fujifilm to m43 will not happen.
Can understand that but the ibis and faster lenses should reduce the need to go past iso3200!
I often want to freeze some kind of movement (people walking etc.), so IBIS will not help. At least if the telelens has OIS, so I can shoot long focal lengths at 1/125s - 1/200s with confidence.
The bigger aperture can help, but will most likely be counterweighted by better ISO on the bigger sensor. And, I rather have f/5.6 on an APS-C system that I already have, than f/4 on m43.
The 50-200 2.8-4 costs $1600 (!), and is kinda big for what it is.
LOL, 655g for 100-400 2.8-4, seriously!
It's not. It's a 50-200mm that can only cover a m43 crop sensor, which result in an image with a field of view equivalent to 100-400mm on full frame. At the same time the light gathering capabilities is worse.
So, at the end of the day you typically end up with similar results as a same generation full frame camera with a theoretical good quality 100-400mm f/5.6-f/8 lens... Or a APS-C camera with a theoretical good quality 75-300mm f/4-5.6 lens. Such lenses could easily be as small, or smaller than the m43 Panasonic 50-200mm f/2.8-4. No problem.
Btw. I don't care so much about the weight. The size is more important.
Would rather have an inexpensive XF 80-300mm f/5.6, which I think can be made even smaller, still with good quality.
It will be more than 650g imo, certainly not less!
There are good full frame lenses in the 70-300mm range with f/4-5.6 and similar weight and size as the Panasonic 50-200mm. A good 80-300mm f/5.6 that only covers APS-C can of course be smaller than that.
Theese are all my wishes for the Fuji system... If someone has other, bigger, lenses on their wishlists, that's fine for me.
I'll finish my post with some wisdom someone laid out here earlier:
"Well, there is room for different users"