I don't own the X-A2, but it's my understanding that it does not have the x trans 2 sensor that is in the X100T, X-T1, etc. I wouldn't be concerned about that too much, because the original x-trans sensor in my X-E1 produces great image quality.
That said, if you can afford both I think you should keep the X100T and embrace the challenge and the freedom of the fixed lens on the T. I'm the first to admit being a gear junkie and desiring Fuji's awesome lenses, but I enjoy the X100T better than any other camera, and I make some of my favorite images with it. Not so much because they are fine works of art, but because of it's size, I have the camera with me more often and get to capture things that really impact me at the time I see them. Even the smaller Fuji inter changeable lens cameras are too bulky for me to carry around on a bike ride, so I pack the T, and when something like this catches my eye, I'm ready to go:
Fuji X....BAAAAM! Renders way different than Sony.
Fuji X....BAAAAM! Renders way different than Sony.