"The problem with the ERF is that you have to take your eye of your subject."
You are talking about a fraction of a second, and not even that if you are using the magnified focus box and focus peaking. Just looking for red in that box is all it takes, I can see that with peripheral vision.
"Sorry, but the ERF is a joke compared to normal manual focusing systems."
Your opinion, mine differs. I find the ERF faster than a normal manual focus system, esp. a rangefinder in the center of the field of view. Focus and recompose takes longer than, at most, just flicking your eye to the focus box and back. To say nothing about a subject close in at wide aperture with a lens that has some field curvature to it...
"Also, again, the focusing scale is in the bottom of the frame. Again - forcing you to take your eyes of your subject to check focus. This is not necessary with rangefinder patches or split prism screens where the focusing aid is in the middle of the frame - where it belongs!"
Focus and recompose is slower than just looking at a patch on the side of the viewfinder showing a focus point that can be anywhere within the entire field of view.
" As you probably are aware, ALL Fuji cameras, including the X100T and X-Pro2 focus both slower and more in-accurately when the OVF is used."
That is not my experience.
Shawn