The advantage of the leaf shutter to me is the flash sync - if I want fill-flash in daylight, it's hard to do it with a focal plane shutter, as most of them top out at 1/125th for flash sync. And most medium format focal plane shutters top out at 1/60th for flash sync.
Yes, that is a distinct difference in the technologies.
However, it depends on the size of the leaf shutter.
Top speed available on a Copal #3 is 1/125 of a second, so obviously it cannot sync flash any faster.
The Copal Square focal plane shutter, used in all of Nikon's second-tier vintage cameras (FA-FE-FG-FM types),
will X-sync at 1/250 because of its titanium curtains, vertical travel and faster traverse speed.
- Leigh