I have a 3 tier system on castor, enabling me to move the keyboards for access to the back of my 19" racks.
It has a Moog Voyager on the top tier next to an MS20 mini, the middle tier holds a Pro8 and 3 monger fingers. On the bottom is a Korg SV-1. So it's got quite a weight to hold!
I'm always worried when moving the stand from the wall that it's going to fall over. It's quite wobbly and doesn't have any cross braces for stability. I even looked to see if I could purchase a Jasper set of braces separately, but unfortunately not. On occasion I have to pull the legs together to pull the bottom horizontal bars back into place correctly. Everytime I move it the whole thing leans to one side and I have to twist the castors to try to get it level again. I'm waiting for the day it all falls on my head ;)
It's done the job, and has been in my studio for a few years now, but makes me very nervous! If they had a sturdier construction with a cross brace or 2 it would have scored higher.