So many boat owners think they are planing when their boat is clearly surfing, going partially through waves not really over. Having driven a 505 doing 9 upwind and then turning down, the amount of boat in the water and the way the boat tracks changes dramatically.
I don't think the modern skiff style hulls truly plane upwind. They achieve planing speeds, but tend to keep the bow knuckle just touching the water. I think the hull behaves more like a catamaran hull in that they don't really develop much of a wake.