I have a Nikon D750 and Nikon D7000 with both DX and FX lenses. I haven't used either for much video but have been dreaming of doing more casual video and wondering if I can justify a used mirrorless kit, despite promising myself a couple of years ago to cut back on acquiring more toys.

I've done some research sporadically over a year or so looking to buy used and have been a bit overwhelmed by the hugely varied tech available. I have been thinking that a "hybrid" camera that would serve as a more compact, lightweight camera that I would carry more often would be justified if it shot "acceptable" stills as well. I'll admit that defining acceptable is very personal and made worse by my admitting to myself that I might baulk at spending more on used lenses of a quality better than kit lenses. I don't carry the D7000 very much. (admittedly I should sell it and get a D7100). I wouldn't go too small because I like a decent viewfinder.

So, today I see listed on the Amazon sale a Lumix G7 with 14mm -42mm F3.5 - F5.6 and 45mm - 150mm F4 lenses for $525 delivered. Unless there are 2 levels of the Pana 14-42 lens that I am not aware of, JB Hifi is selling it for $449 alone. Of course, this sale ends in a days time, so it's a classic FOMO-pressure purchase scenario. I'm tempted but in the knowledge that a camera released in 2015 foregoes years of improvements. I realise that these lenses are pretty ordinary, but if I treat the camera as a video device and happy snapper or travel camera they may be acceptable.

I haven't found a compelling used camera of this calibre with better lenses advertised under $1000. I could probably budget to that much and maybe get at least one better lens later, but then I'm likely to dither much longer.

I'm intrigued by the possible usefulness of 4K Photo mode or 4K burst mode to capture stills in action scenarios as compared with fast/continuous shutter on my two Nikon DSLR's. I'm only really interested in 4K video to use it to capture stills or possibly crop video in the future. I don't even have a 4K TV or mobile phone.

I am also indecisive about going to 4/3rds instead of cropped sensor mirrorless. But I would use the D750 for low light etc situations.
I'm hoping I wouldn't want to crop in post heavily with the 16MP sensor of the G7 compared to 20MP models, especially with cheap lenses.

Some questions I have:

Does anyone have experience with this kit?
Does it play nice with other brands of 4/3rds lenses?
What is the shooting experience with Panasonic 4K Photo Mode like?
How much difference doe in-body stabilization make? I've learned that requirement restricts choice of brand, or to later releases and requires a bigger spend on the body.