10 years ago I owned a Canon DSLR with some L lenses, and a Canon SX60 bridge camera for light grab and go shooting. All of my photo friends also owned some sort of full frame or crop DSLR. Then...one day I was visiting a friend who had just returned from a safari in Africa and was looking at her really striking images, I inquired about which of her lenses she was using for the images. She said 100-300, which was strange because I didn't think she had any Canon 100-300 lens. She informed me that she hadn't taken her Canon DSLR kit because of the weight limitations of the small planes that were to take them into the bush, and had purchased a Lumix GX7, 100-300 and 40-140 lens the week before the Safari.
I was so impressed with the images she had taken that I asked to borrow the GX7 and compare it, shot for shot against my SX60, which as it turns out was about the same weight as the Lumix. I then sold the SX60 and purchased my first M43 camera, the GX7. After about 6 months, the Canon DSLR was sitting on the shelf and I had added a small Olympus to the growing cadre of Panasonic m43 lenses. I had never intended to do a complete replacement of my Canon DSLR, but rather to just add the M43 kit as an adjunct for something smaller and lighter.
Another side note..... when my wife and I joined our camera club we were the only members shooting m43 (and mirrorless), all others were shooting Canon, Nikon, or Sony DSLR (FF or Crop). Today with everyone about a decade older, and all of us in our 70's (and some older) 20 of the 25 members of our club shoot mainly m43. We shoot a lot of birds here in Florida, and many members travel extensively. The smaller, lighter, and extra reach of the m43 seems to fit particularly well with our "middle age+" members. The great image stabilization helps with older twitchy hands, too.