Regarding the OM-3, IMHO, it is a completely different comparison. The OM-3 is an OM-1.2 in different clothing. I would say it is worth upgrading from an EM5 MKiii because of the sensor (stacked BSI), bigger battery, USB C, the new menu, and of course it is snappier in use. Then there is the front creative dial from the Pen-F that I actually enjoy using. The CP button is a nice addition over any of the previous camera versions, including the OM-1.2. The dedicated dial for stills, video and slow motion is also kind of interesting as well. I briefly played with the slow motion and while I doubt I would use it much (I don’t do a lot of video) I can see occasions where it would be fun.
There are misses for me, namely a threaded shutter release, the missing ISO button, and the missing front FN button but I will survive. I already have the Olympus Bluetooth remote for the OM-1.
Personally, I think the price is reasonable for a camera that has a stacked BSI sensor and all of the various computational features that most other manufacturers do not have. The weight is a little more than the Pen-F but much less than the Zf. I love the Zf but I found it too heavy for me and then lenses on the whole are going to be larger than my MFT and Leica M mount lenses. My sweet spot for a dual carry is an M body and a MFT body and the OM-3 is a perfect addition. I can have a zoom or an AF prime on it or use one of my M lenses that I am carrying anyway and double the reach, an M mount 75 or 90 is perfect for a small mini telephoto on a MFT body.
Hopefully this helps you and others. I think this camera will sell well, but what do I know? When people complain about the price, where else can you find legendary weather sealing, a stacked BSI sensor, class leading IBIS, features such as in camera focus stacking, live ND and GND, Pro Capture and Live Composite among others. When I talk to other photographers who have only used Canon or Nikon and I begin to explain what an Olympus/OM Systems camera offers, they are amazed at the images I can get in such a small body and small lenses. Shooting with MFT as you know is a different mindset compared to FF which many do not understand until they actually see the benefits in person/use. I am not saying MFT is better than FF because I love FF as well, particularly my Leica bodies. They have benefits that MFT does not have, I see all cameras as tools that meet specific wants and needs, at least for me.
Good luck with your decision 👍🏻