1 week or so with the cat condo and so far I'm entirely satisfied with it.  Both cats are "robust" and the bigger one is almost 13 pounds.   Both are a bit older, so there is more snoozing than playing on it.  It is plenty stable for both of them.  At first, I thought they were not going to be able to get to the top bunk, but the smaller of the two is able to manage.  He sometimes will go tier to tier and pop out the window in the tube, then use that as a step to get up.  And, when frisky, he'll scale the long post all the way and heave himself into the bed at the top.   The big guy has more trouble navigating the turns required for those manoeuvres but is happy in the second bed or the tube.  I'm hoping they don't tire of it... it's good entertainment watching them on it.  "Should have bought it years ago".