I've seen a few slalom sailors have a go during the day in the easterlies, but I think the wind just doesn't have the same fetch and quality as the Applecross area.
Al, Max, myself and some German tourist sailed the narrows at night a while ago. It was pretty surreal, but the water was definitely more gross than Melville/Peli Point area.
We sailed it 5.2m pretty powered up from memory. Water was relatively flat near the South Perth side, but drops to nothing around the Narrows. I think the wind prefers to go over rather than through. A few boats were driving around kicking up some ramps - I think they were pretty surprised to see us!
Best memory from the night was Max's night blindedness leading him to unknowingly sail full power into the shore and dissapear into the darkness. haha