Climbing at 8000m: Double Boots suitable for the highest mountains in the world. Some of them, like the Vega, will be equally good for Scottish Winter and the Alps.
Climbing at 7000m: Double Boots suitable for use up to around 7000m and Alpine Winter climbing.
Climbing at 6000m: Boots suitable for use up to around 6000m. Obviously, they will be equally good for Scottish Winter, Continental Icefalls and Summer Alpine. Use by some for Winter Alpine, but if you want to be sure of your toes, use double boots.
Scottish Winter & Summer Alpine Climbing: Boots suitable for use up to around 5000m. Obviously, they will be equally good for Scottish Winter and Summer Alpine.