I have tried beds across and the water simply runs through them in a heavy storm, causing more erosion (of compost from beds) than from paths which were going up and down. So for my slightly-raised beds, I like them to be up and down a slope, and think that Keyline is good for farming where there are not beds.
Soil from path to bed is good when clean of weeds, it does give a more raised bed than from compost only, which tends to settle.