Well, the Nikon is a completely different camera from what you asked for. In that case just get a GFX100S, put on a 30mm lens and call it a day. More money, but you want to talk about best in class imaging? This effectively ends the conversation. Handheld 100 megapixel medium format with IBIS? Now we're talking.
But, at the end of the day, I still have my Leica Q2 and Q2 Monochrome (I have my Ms too, but I am seriously thinking about deaccessioning). They are fabulous cameras. The image quality is absolutely stellar, easily exhibition worthy and at 24 x 36", you will struggle to see a difference between that little point and shoot and the GFX100S although the aspect ratio will give it away. The color science is fabulous on the Q2.
There is a lot of myth weaving around Leica and much of it is unwarranted, but the build quality, the easy-to-use menus, little features like the button for setting an "zoom" crop for jpegs (I keep looking in vain for this for on my GFX100s) or the twist ring you can use to shoot macro make them a complete delight. Heck, even the much maligned Leica Fotos app just works for me.
Great post, thanks. I've sent you a PM - did it get through to you?
I've swung back to the Leica Q2 (I really need to get my hands on one) but I'm just not sure if it'll be as reliable and robust as one of the 'sportier' mirrorless or DSLR cameras from Canon or Nikon or Sony.
I'll be undergoing a lifestyle change soon which will involve living in the bush/mountains for a long period of time (and being completely self-sufficient). I'll be doing a lot of photography to document my experiences.
I'm thinking it would be an absolute pain in the arse to have to send gear away for repair, because it'll mean walking hundreds of kilometers to the nearest large town.
If I take heed of what the photographers who shoot in the most demanding conditions use (war and wildlife, and perhaps some hardcore landscape photographers) - most are using DSLR's or Mirrorless cameras from the likes of Canon, Nikon, Olympus, Sony etc. Not many digital Leica users.
Is this an indication of these people requiring more flexibility from their cameras than what a digital Leica would afford them, or are those cameras actually more suited to being banged around and enduring severe weather?
I love the look and simplicity of the Leicas, but I think the novelty would wear very thin if I experience any reliability issues, and/or have to send it away to Leica Germany and have to wait months for a repair.
I'd appreciate some thoughts from working photographers who shoot in crappy conditions.
Lugging around two bodies (in case one malfunctions) could be an option, but I'm not a paid photographer, so I'd rather not.
I know I said I hated bulky and/or weighty cameras, but if the only way of getting a tough/reliable camera is by making peace with those characteristics, then so be it.

Thanks again for your input and suggestions. I've considered every post in this thread.