A quick update to the stairs question about an a4039 or similar Avenger lazy leg steel stand. By maxing out the two upper legs within the stair tread and fully extending the lazy leg, I can NOT make the stand vertial on interior stairs. It's off a couple of degres to the lazy side which really impacts the stability. Now this isn't weighted, but any pull to 45 degrees of either side of lazy is going to tip. Normally you boom over a leg, so unless you are booming straight down the stairs it will be unblananced without a mess of weight.
FWIW, reducing the leg spread will further increase the angle of tilt and additionally, the base of the center shaft will contact the stair tread and make it all even more unstable.
0S4A3286.jpg by AeonFilms, on Flickr