Nevis Red vs practically every black in the country.
The colour system’s just too crude tbh, individual trail gradings could be better but you really can’t do much with a 5 point grade scale. I like the idea of keywords, so you might go Red-fast-flowy for Glentress red, Black-long-rough for Glentress black, just basically take the 2 or 3 words that pop out when you describe the trail.
Gradings will always be subjective though, if you send someone who’s good at jumps down a jump trail they’ll say it’s easy, you might send them down a rock garden next and they say it’s black, next rider could say the opposite.