Thinking of Moving from APSC to M43

Peter 1745 Factor the purchase of one or two extra batteries into your budget.

Good point in batteries. I switch with the coolpix and carry 3rd party spares so don't mind that. One thing of note with Nikon is for the DSLR a firmware update stopped a lot of 3rd party batteries working which is a shame as they are 1/4 the price of an official battery. Thankfully I didn't update my firmware. I can understand why manufacturers do this as they need to protect their reputation. Even official batteries can have issues. like the samsung note recall. Do 3rd party batteries work on M43 or do certain firmwares run risk of disabling them?

Since you mentioned the G80/G85 specifically, one thing you might find interesting in this respect is the new "Economy Mode" that Panasonic has added. It uses a more aggressive auto-sleep when the camera is away from your eye, and with it Panasonic claims that you can get up to 800-900 shots with it. Obviously, you don't get some of the mirrorless advantages of always-on Live View when you're in this mode, but you basically end up using it like a DSLR and getting DSLR battery life as a result.

That said, battery life has never really been a concern for me and my GX7. I have a variety of inexpensive 3rd party batteries. As long as they are "full-coded" I've never had any issues - battery gauge in camera is accurate, and no problems charging. And as you say, they tend to be about 1/4 the price of an OEM battery. They have less capacity in the real world, in my experience, but the you're still getting, say, 3x the bang for buck.