Very interesting product. Definately something that would help in any mountaineering endeavor, But I would not recomend "rushing" up a mountain like everest. It says on the site that it can simulate up to 20,000 feet. Everest is 29,000 feet.
Also, there is alot more to the 70days then just increasing the oxygen in your blood. Acclimatizing on a big mountain also gets you more used to the temperatures, and phisical strains of climbing. Unless you spent the previous week on another 8,000 meter peak, you will not be ready to summit, physically or mentaly.
Even the most elite climbers with ridiculous VO2 levels spend alot of time acclimatizing at base camp. That product, would definately be a valuble addition to the acclimation process. But I would not use it "in-sted of"
I have no experience with high altitude mountaineering, but I have spent a lot of time studying it. And like you, I have a dream of summiting everest, and all the other 7 summits. I may never accomplish this goal, I have other extreme endurance fastpacking goals that will come first.
But if and when I do climb everest, I will in no way rush the process, It is an attainable goal, but one that comes with extreme risks, "Rushing" or not being completely prepared only add to your risk.
I understand your reasoning, but I would recommend trying it out on a "safer" mountain first, and before attempting everest, Denali and cho-oyu would be valuble climbs to have before challenging everest.
Im guessing you are not planning on using a guide company. aNy reason behind this??