All very interesting, but hey! sanity check boys & girls: someone died on the “easy” red @ Swinley a month ago. I’ve ridden Swinley red since & the bit where it happened is a decent, but not enormous & very rollable, jump. Only a confident & skillful rider would get hurt there, because only a reasonably good rider would be going fast enough to get really airborn, a beginner would just roll safely through @ a bit over walking pace & wonder what all the flowers were for.
Mountain biking is fundamentally dangerous. Fast tracks are more dangerous than slow ones. As far as I’m concerned grades should warn people of that. Technical difficulty with no danger, like off camber roots & stepped climbs, we can find out about as we go along. IMHO.