I had the Leitax mounts on two R lenses and used them on the Nikon F body. Plain prism head so metering was irrelevant, and a Type A screen so that when the split-image blacked out it wasn't much of an issue.
I tried AAA lever gizmo and found it too fussy for my taste. Shooting mostly wide open and near-wide open worked best, just focus stopped down.
But ultimately I replaced the focal lengths with Nikkors for use on Nikon mount bodies and returned the lenses to their Leica R mount. That works best—the good Nikkors are themselves very high-quality lenses and they work well with F, F6, and D750 bodies. The Leica R lenses work best on Leica R bodies and the Leica SL body.
G