Think of the gimmicks this way. If you live at sea level, your body adapts to that. If you travel to "high elevations" and stay there for days and weeks, your body acclimates, but it takes a while. Your body adapts to where you live, whether at sea level or high elevation.
So, if you work out an hour a day every day with your gizmo (most won't do that much) but you live at sea level, do you really believe your body will adapt to how it spends 1 hour a day vs. the other 23?
As far as hitting your aerobic threshold and raising it, read up on interval training.