I don't see where the 280 is underated at all. Everybody knows exactly what it will do and for the most part for 99% of hunters that is exactly what the 270 does.
Both cartridges are excellent in many regards the 270 just won out due to years head start, Saami specs, and ammo availability.
I believe underated means most folks don't believe the cartridge will perform as well as it does. That definitely is not the 280.
