Jerre may want to pipe up on this, but the pictures are from a Mark Aspery class that we both attended and his stand was really pretty steady. they wide tripod legs helped quite a bit. Note that the center beam does not extend to the ground so you only three contact points, making it pretty steady even on un-even ground.

I just checked with Jerre. His weights in at 96 lbs (that's the stand and vise together) and is pretty stable. He said that there are small plates welded on as feet and when he needed a little bit more stabilty, he would step on one.