I use Micro 4/3 as my main system, but as many users here I like to experiment with more than one camera or system. While browsing in the forum I became curious about Pentax, (I never shot a digital Pentax before) and that is how I got a K-1 and then a K-5 IIs.
The cameras feel great in hand, you can immediately feel "quality" while grabbing them, the buttons and dials are are close to perfection, I use a lot the little LCD screen, the grip is fantastic, if anything I would add a joystick to both and a tiltable screen to the K-5 IIs.
Transitioning from an OVF to an EVF was easy, transitioning back from EVF to OVF was a little bit hard at the beginning, but with some time I became used to the OVF again. And I have learned to like it more than I thought at the beginning! I'm not bothered by the smaller OVF in the K-5 IIs, honestly it is not an issue for me (I wear glasses).
The image quality of the K-1 for a 2016 camera is second to none (as I expected), but the real surprise turned out to be the K-5 IIs, when you consider the camera was released in 2012 there is nothing to complaint about! 11 years later and the image quality is excellent for the vast majority of users. The .PEF or .DNG files are very malleable in post, delivering very crisp and vivid results, and the camera has an ace up its sleeve: an ISO 80 setting that I always use as a start point. The Pentax colours, along with Olympus, are right on top of the market. Another great Pentax feature that is present in the Micro 4/3 ecosystem is IBIS, Pentax calls it SR (Shake Reduction) and while not as effective as with Micro 4/3, it is no slouch. One feature that I still really want to try with both cameras is the unique Pentax Astrotracer.
At the moment, I have two "modern" DA lenses, the 20-40/2.8-4 Limited and 70/2.4 Limited, both of them superb, they render just the way I like it, which IS NOT "clinical-ultra sharp-sterile" images. With my K-1 I only use vintage K and M42 lenses.
The "Achilles heel" of my Pentax K-5 IIs is shown when you compare the AF, simply because there is no comparison, period. Single AF in Micro 4/3 is ultra fast and accurate, this is not always the case with the K-5 IIs. That doesn't mean that AF is unusable, but the reality is that I don't trust it entirely how I trust Micro 43 in that regard. (But hey! Keep in mind that the K-5 IIs was released in 2012, so it is a little bit like comparing apples to oranges and it wouldn't be fair).
The good news is that there is a walk-around, which is to AF in live view, that seems to give me the desired results most of the time. The K-3 III might be a different story, but I have no experience with it (maybe one day
).
To conclude I will put it this way: I don't see myself shifting away entirely from Olympus/Lumix to another brand, because as I have said before, Micro 4/3 for my usage is the perfect balance between, size, cost, reliability and results. But at the same time, the Pentax "experiment" fed by my curiosity turned out to be a very pleasant experience, it is undeniable that for the money Pentax gives you so many features not present in the competition. That is why, unlike I did time ago with Canon and Fujifilm, I don't see myself selling my Pentax equipment and lenses any time soon, on the contrary it is likely that I will add another lens soon.