You know, that's the interesting part - I'm not so sure the safety is any higher percentage than the jump. From time to time, I'll do trick shots for corporate events and one of my shots is jumping an objectball over an obstruction (like a cue). I know I can get the objectball to hop about an inch so it's a shot I'm kinda familiar with. The unfamiliar part is jumping over the edge of a ball. It's really difficult to measure. I figured since it was only a small portion of the object ball that I wouldn't need much to clear the 7 which is why I went this way.
Had a really tight safety been available (the frozen kind), I definitely go that way.