MtL:
The Versaclimber works just like the star climber machines in that the ‘stairs’ fall away from under you rather than you having to lift your body’s mass upward against gravity. So they really do not perfectly mimic hiking up stairs or hills. They require less work. But they do serve a purpose for those trapped on flat ground. The reason to hike up hill is to build the specific strength endurance for climbing mountains and the Verss will do a better job than say biking while seated or swimming or even easy running on the flats. The Versa does allow you to adjust step hight on the go so you can mix it up. But in terms of specific training effect for mountaineering/alpine climbing, I’d rank the methods you mention here in this order:
Steep Hills
Stairs
Box Step
Versa Climber
Stair Master
Treadmill
Scott