I use these types of stands all the time at work, and have particular experience with the American DJ models. What they don't tell you is
A) the weight limit is based on zero vertical extension. The locking collar that holds the vertical bar is just a plastic friction collar and it will slip vertically at much less than 200. And they get weaker with age as the aluminum tube and collars get polished and smooth. Generally anything over 60 pounds vertical will start to slip
B) The tubing is very thin walled and it only takes a small dent to weaken it enough to fail. I've had them fall when one kid tripped and landed on a leg at a dance party.
C) Those vertical masts are rated for ZERO lateral load. You could do the truss across the top but only if you hand from the truss itself, not the masts.
All told, you'll get off much cheaper and lighter with three 2"x2"x8' pieces of lumber and when folded up they will pack to a smaller diameter than those speaker stands do.
Edit: Although, yes, the stands would collapse to a shorter length. IMHO, the only way they would be superior.