Interesting thread.
I am a long-term OM-1 user and an EM-1 before that. I moved from Full Frame over 10 years ago due to the weight.
The OM-1 can do all sorts of amazing things; it does have focus peaking, and the subject tracking on humans, birds and animals is as good as most other cameras. and it is especially good at wildlife and macro imho,
The one thing it lacks is dynamic range; the sensor in it is now 10 years old. So, landscape photography is not its strong point.
I am actually thinking of going the opposite way and considering the Sony A7R V or even the VI if it is released soon.
The question you need to answer is what it is that your current Sony can't do that is impacting your photography.