Just for what it is worth, I would highly recommend you consider the A7iii and 70-300mm lens as a compliment to M4/3. I had the A7ii and I had the 24-240mm, and I was not totally happy with either. But the A7iii is a totally different beast, with much more to offer, and the 70-300 is incredibly sharp. You can also pick up a 28-70 kit lens for next to nothing, and that is hugely underrated. I'm just offering my experience as an Olympus owner and a Sony owner.