On Himalayan climbs, good hiking boots (hard or flex soles) will suffice till base camp. Single boots like La Sportiva Nepal Extreme can suffice (in combination with gaiters) till maybe 6000 M peaks including the approach march to base camp. But they fall short at higher altitudes.
Are high altitude double boots, e.g. the Millet Everest Summit GTX, or the Scarpa Phantom 8000 or the La Sportiva Olympus Mons etc. usable on lower altitudes, like 6500 meters? Or will they be too hot?
The point being, suppose someone wants to acquire a single pair of mountaineering boots that will suffice across all altitudes - is this realistic?