Until recently I was the kind of photographer who had a camera for every use. Canon 80D for wildlife with a Sigma 150-600, Leica M10 for street, Sony RX10 for travel, Fuji X-T2 for best user experience. When I came home from a two month 13,000 mile RV trip across the US, Canada and Alaska, it had become clear to me that the X-T2 was the only one of them I truly enjoyed using. In fact, when I tallied up the number of shots I had taken with each camera, I found the X-T2 was the resounding winner at 93% of the 3500 photos from the trip. So, I sold all the other cameras and lenses and bought an X-T3, keeping the X-T2 for when I need more than one body/lens ready for wildlife while shooting landscape. Now the X-T2 sits idle most of the time while the X-T3 gets all the use. This is the best decision I've made about my camera gear in several years. The lure of full frame cost me lots of $, but the theoretical advantage over APS-C never materialized in my use and the Fujis are so nice to use. I guess I'd have to call myself a "Fuji guy". at this point.

Until recently I was the kind of photographer who had a camera for every use. Canon 80D for wildlife with a Sigma 150-600, Leica M10 for street, Sony RX10 for travel, Fuji X-T2 for best user experience. When I came home from a two month 13,000 mile RV trip across the US, Canada and Alaska, it had become clear to me that the X-T2 was the only one of them I truly enjoyed using. In fact, when I tallied up the number of shots I had taken with each camera, I found the X-T2 was the resounding winner at 93% of the 3500 photos from the trip. So, I sold all the other cameras and lenses and bought an X-T3, keeping the X-T2 for when I need more than one body/lens ready for wildlife while shooting landscape. Now the X-T2 sits idle most of the time while the X-T3 gets all the use. This is the best decision I've made about my camera gear in several years. The lure of full frame cost me lots of $, but the theoretical advantage over APS-C never materialized in my use and the Fujis are so nice to use. I guess I'd have to call myself a "Fuji guy". at this point.

You are giving up one great dSLR to use a great MILC. You should enjoy the Fujifilm XT-3. It is getting rave reviews from nearly all review sites.

Fujifilm is known for their excellent in-camera JPEG processing, their film simulations, and their excellent lenses. Even if you are an, "I only record raw files" sort of photographer, you should try all the Fujifilm JPEG modes. Many folks who used only raw files from their Canons and Nikons use JPEGs from their Fujifilm bodies, at least part of the time.

When I worked in graphic arts back in the 1980s, we had many Fujinon lenses on our big copy cameras. They were amazing. Fujifilm doesn't have the lens line-up of some other brands, but they have mostly the right focal lengths, and nearly all of them are top quality glass.

Mirrorless is a very different approach to photography. You will see many advantages and a few disadvantages. Whether the disadvantages bother you or not is a matter of situation. It would be a very good idea to force yourself to read the manual, even if it is broken English. These new mirrorless cameras have lots of hidden advantages that need to be understood and tested to be appreciated. You may have to change some of your habits to get the most from mirrorless — I know I did.

I'm a Panasonic Lumix user, primarily because I need the advanced video features in the GH series. But if all I used were stills, I could use an XT-3 and love it. It feels great in hand, and has the same sorts of well-placed physical controls (buttons, dials, switches...) that the top Lumix models do.

The Fujifilm system lenses may not save you significant weight. If you still need a lighter SYSTEM, the top Micro 4/3 models WILL save weight over APS-C and full frame systems. The Olympus OM-D E-M1 Mark II and the Panasonic G9 and GH5 are in that class.