Boy you sure opened a can of worms here. It's the old Nikon/Canon argument all over again. I switched from Nikon to a Fuji X-T1 back in December 2014. Have changed to an X-T2 and also have an X100. Best decision I ever made.

This is exactly what I did - back in 2014. Sold my Nikon D90 and lenses and went the Fuji way.
I already owned the Fuji X100 and took it with me on a trip to Europe in 2013. By the end of the 2 month trip I was using it more than the D90 and loving it. Came home and did some serious research and bought the X-T1 with the 18-55 and 10-24.
I could not be happier. I am a 1951 model so similar age and I have found my photography has improved in leaps and bounds which I put down to lugging less around with me and being more flexible in what I take. Don't use a tripod as much and it's just so easy to pick up and go.
Do it - you will never look back at the Nikon's you have.

If travelling I put them in my holder face up to start and then when full and until I can download them and re-format I place them face down. Can see at a glance what's been used and what hasn't.

Domestically I've travelled with it as carry-on and had no problems. I've just returned from 3 months in Europe where I carried it in my suitcase. Like you I felt I needed it for long exposure, night shots etc but found out I didn't really use it as often as I thought I would. It became a pain carrying it when I thought I'd need it and then being able to get what I wanted hand-held. I would not take it again - it came down to me carrying it somewhere just to justify taking it away with me lol.