Manual focusing for adapted lenses depends only on the camera performance. Newer bodies have faster internal CPUs so focusing with adapted lenses is very responsive.
The manual focusing aids on the X-Pro 3 are:
o The Manual Focus Indicator - an in-finder graphic simulation of a lens focus scale. This doesn't apply (and is not needed) to adapted lenses.
o Focus Zoom - improves visual focus assessment
o MF Assist
- Digital Spit Image
- Digital Microprism
- Focus Peak Highlights
For me, most importantly all these focus function can be used with the optical view finder. I find the focus peak highlighting to be most useful.
Once you understand and experiment with these manual focusing aids, you only use one.