The XT100 sounds neat. I wouldn't mind trying one to see the difference between the Bayer and the XTrans sensors. The X70 was on my radar for a time but I ended up with a Ricoh GRII instead, which I like a lot although it's a dust-sucker. Don't forget about a used X100 series, really great cameras but still expensive for the later models.
For your purposes the XT100 might be perfect. I was going to recommend a used XPro1 (I love this camera!) until I saw that you do "dog shots". As much as I love my XPro1 cameras, I have to admit they ain't gonna ever be classified as action cameras and my dog is all about action. If yours or the dogs you photograph are like that, you probably would do better with a used XT1. It's not a perfect action camera either but, with the right lens and updated firmware, it's better than the XP1 in this regard. It's a bit more expensive used than an XP1 but it was cheap enough a few months ago for me to buy one--geez, I need to get rid of some stuff!