I was out wandering around today and I walked by a big Yodobashi camera store so I went inside. Nothing particular I wanted to look at, but what the hell, fun to see the tons of camera gear all sitting out for anyone to play with and no sales people hovering around you. I played with the Sony A7C again, Sigma fp, and a few others. All I had held and played with before. Pretty much anything (bodies, lenses, etc.) are out for you to play with at these big camera stores in Japan. I walked by the Olympus section and the 100-400mm f5-6.3 was sitting out and since I had my E-M10II + ECG-3 + 14-150mm II hanging from my neck I mounted the 100-400mm on my camera. The E-M10II has the latest firmware. The last few times I was at a store that had the lens I had my Panasonic TX1 (ZS100/TZ100) so I was not able to take any photos on my own body.
I took several photos in the store at the maximum 400mm (800mm-efl). By mistake I took a few photos that had my body IBIS set to S-IS AUTO and the lens IS also turned on. My understanding is that with this body and this lens you should choose one form of IS or the other, not both. The results were fine though so I wonder if one of the 2 forms of IS was automatically turned off? Take a look at the shutter speeds. I was holding the lens and body normally (right hand under the lens) and making a reasonable effort to be steady, but I was just standing there and not making any extraordinary effort to be steady. These first 2 photos are from about 10-15 meters away.


The next photos were from about 30 meters away.

I turned off the body's IBIS and only had the lens IS turned on:

I turned on the body's IBIS and had the lens IS turned off:

I would say the IBIS in even the E-M10II is darn impressive!
I wrote the following about modular m4/3, the E-M10II specifically, in February 2016:
https://www.dpreview.com/forums/post/57203605
The Pleasures of m4/3
For me the pleasures of using m4/3 runs in 3 directions depending on what kind of photography I am doing:
1. Bodies and lenses with similar capabilities to my previous DSLR gear are smaller and lighter. When I travel the decrease is really appreciated! (The GX7 can do this too.) For example, when I travel I take the following:
- Olympus E-M10II + ECG-3 grip
- Olympus E-M10 + ECG-1 grip (I wish both cameras used the same grip because then I would only carry one)
- 4 batteries and charger (both bodies use same batteries)
- Olympus 14-150mm f4-5.6 II
- Olympus 9-18mm f4-5.6
- Olympus 25mm f1.8
- Olympus 9mm f8 fisheye
2. Then at other times I really love the small, excellent, prime lenses. (The GX7 can do this too.) I take off the ECG-3 grip and mount one of my small lenses (and sometimes carry one or two more in a pocket):
- Panasonic 14mm f2.5 pancake
- Panasonic 20mm f1.7 pancake
- Olympus 25mm f1.8
- Olympus 45mm f1.8
3. Then at yet other times I take the grip off and mount the Olympus 14-42mm f3.5-5.6 EZ pancake to turn it into a better LX100 of the same size:
http://www.dpreview.com/forums/post/57047115
Some people prefer the bigger cameras such as the E-M1, GH4, GX8, and G7 which are always big and are not modular with a removable grip. Maybe they also are usually using the larger f2.8 zooms, 300mm f4, and 100-400mm f4-6.3 which make the most sense on those larger bodies.
The great thing is that there is something for almost everyone!
A point that may have been missed
https://www.dpreview.com/forums/post/57244058
I think that probably some people missed one of my points and that is because I didn't state it explicitly. When I wrote the OP I decided to instead make one of the points by way of example. The point made by example is that, at least for me, my choice of m4/3 gear using the same body fills 3 roles that otherwise would likely involve 3 different cameras.
The modularity of the E-M10II (and E-M10, E-M5II, and E-M5) which have add-on grips which one can optionally use along with the plethora of lens choices of many focal lengths, apertures, and sizes allows me to use just an E-M10II and depending on whether I use the add-on grip or not and depending on which lens I mount it can be a completely different sort of camera, but retain the same great sensor, the wonderful IBIS, the excellent EVF, same battery, and I don't have to get accustomed to a different interface, menu, etc. Before m4/3 I would more likely have 2 or 3 different cameras to fill the spots that just my E-M10II currently fills. These days when I travel I take the E-M10II and E-M10 (backup). Same batteries for both.
The only other camera I take with me when I travel is a very small camera. For the last few years I have used the 1/1.7" sensor Canon S95, but I may update to a Sony RX100 or Canon G9X one of these days. All 3 cameras are almost the same size, but the RX100 and G9X have 1" sensors. [Got a Sony RX100 in 2018.]
My PEN-F is great and I use it sometimes when traveling too. Then in January 2020 I bought an excellent, used GX7II (GX85) in Tokyo. My first used m4/3 gear. Here is my user review:
https://www.dpreview.com/forums/post/63703723
Oh, I added the very nice Olympus 75-300mm f4.5-6.7 a few years ago. I rarely use it, but it is another m4/3 gem. Small and light and quite sharp even at the long end.