This is a hard thing to do but in the near future I'll probably be marketing my 400DOii.
Though the Sony FE 400/2.8 is not exactly what I want, and since the DOii is almost the last
remaining EOS lens I have of any import, it is getting close to time to send it off to another user and
be all e-mount Sony.
What would replace your 400 DO II ?
The Sony 100-400 ?
I'm interested in the 400 DO II. I especially like the way it performs with 1.4xIII. I've rented this lens before and have enjoyed it.
But for now I'm holding off on buying any expensive gear. Nikon may offer a mirrorless camera and a 500 f5.6 lens. Canon may come out with the 7DIII. And I still have my eye on Sony's system. Lots to consider. I'll give it another 6 months and see what shakes out.