Hmm, missed this when it was first posted.
I'm a little behind in the rapid pace of the smaller companies mirrorless development, but I can share my own experience.
I love the Fuji Xt1 for many aspects. People spent a LOT of time on this forum convincing me that the XT1 and SONY of the same era, (a7II I think? Maybe a7?) had EVF that would satisfy a wildlife shooter like myself, and AF that would do the same.
ANECDOTE #1:
So I included it in my last trip to Africa (summer 2017). The Fuji kit included a long telephoto OIS zoom lens, and the fabulous 18-55mm "kit" lens.
That Xt1 which I love to shoot around the campfire, candids, and impromptu scenics, was TERRIBLE for shooting wildlife. Between the EVF, the lackluster AF and overall response time, it was an absolute no go.
Another friend on our trip (the guide in fact, Dave aka "CondyK" on this forum) also packed an XT1, and was positively disgusted with the choice, despite the fact that he too had grown to love the XT1 for his urban shooting around the UK. We also both suffered from constant battery anxiety, with the little Fuji batteries offering up often maybe 1/6 the shots that a 7D2 would with an OIS lens attached.
So I stuck with the 7D2 and 5D4, I loaned Dave my back up 1D4, and we essentially carried the Fuji's as extra weight. (Dave's main body was a Nikon D500 with the 200-500mm, and excellent combo!)
I realize the XT3 is out, and things have changed, but at the time, every Fuji shooter I talked to guaranteed me that the XT1 was THE ONE that would get the job done. When in fact, it absolutely could not keep up with a 7D2.
ANECDOTE #2:
The following summer (2018) I was in Newfoundland, and had two decent birding opportunities.
"Bird Rock" at Cape St. Mary's, and Puffins at the Bona Vista light house.
In both locations, despite harsh cold weather and or rain and HEAVY fog, the 7D2 (and 5D4) were amazing. At Bona Vista I was getting very high % in focus shots of Puffins in flight!
At Bird rock the BIF are Gannets, big white birds with 6' wingspan. In heavy fog (actually makes it easier for AF to pick up a BIF, with no busy background to distract) it was like fish in a barrel.
In both locations there were people with Sony A7, at least up the A72. I think an A7III in one case. At Cape St. Mary's there was a wildlife tour from the states in fact. I listened to them all complaining about the inability to get flight shots in some of the easiest conditions. If those A7 can't do it here, forget about it.
At Bona Vista it was just one gentleman who approached me to ask how I was doing. I scrolled through shot after shot of in focus puffins darting overhead, and his jaw dropped. He did not have a single in focus shot of a puffin in flight with his A72.
I posted these experiences in both cases after I returned on this forum, and in both cases I received flak, and excuses, "the Fuji Xt2 has fixed ALL that, now it's perfect" or "They didn't know how to use there A72" "you need the A73 or the a9" etc. etc.
Now the EOS R is out and you can look at the thread, and see just how few examples there are of that kind of wildlife shot.
I am sure the a9 CAN handle the task I ask of a camera, but other than that, right now, i am not sure there is anything lighter than a 7D2, particularly in the price bracket, that can do what it does.
If this thread were posted in other other sub forum, I would leave it alone and assume that losing weight and going mirror-less was a good idea. But here in the Bird forum, I feel compelled to share my experiences and offer my opinion that with VERY few exceptions, smaller lighter mirror-less options are not up to the task of birding.
