Three posters and all diminuishing a new camera from Olympus, tsk, tsk, tsk...
If that camera isn't for the four of us, it still isn't "General Custer's last stand", "in a mad formfactor", "making sense with only a 300/2.8 lens".
If you need to compare it weightwise, daver, then don't go apples and bananas, dave: It's a µ4/3 D5, the battery grip is unseparable. And then we're talking about a miniaturized D5 - does it make sense? I don't know, for a Olympus owner it probably does, because he or she already accepted the shortcomings of a very small sensor. So stop comparing it to FF types without a grip, it's plain stupid.
Mad form factor, Klaus? BS. Within the Olympus cosmos it will find it's buyers, even if none of us knows a Pro shooting in µ4/3.
And BC, you're old equivalencing babble is for the trash. Shallow DoF will never ever be the main reason to buy µ4/3. How about this lens: https://www.dailycameranews.com/2019/01/...converter/
Olympus has rather capable, fast lenses, and this kind of ruggedized, highly weather sealed body will deal with more harsh conditions than the majority. The whole package doesn't give a price advantage (as only miniaturisation never does), but compared to a similar FF professional system it will be lighter and smaller.
There are not that many 150ish - 400ish zooms with constant f/4.5. For FF, that is. In reality FF would need a 300-800/4.5 to go along. Again I'm not talking about DoF, I'm talking about fast shutter speeds.