I have the stainless cheek plates as well, but they did not prevent my clew slug from blowing out of the track and parting the outhaul last night. The wind was in the low end of the #3 range, so the main was fully loaded.
Upon inspection back at the dock, it became apparent that a previous owner had moved the cheeks down away from the slot by about 2mm. The lateral force on the main caused the windward edge of the slug to pry out of the slot, distorting the aluminum.
So, be sure the cheeks are mounted flush with the slot AND use a tie-down strap for redundancy. Hindsight...
