I put one 35 - 40 lb SkySki on the side of my Titan all the time..... plus over 100 lbs in speakers. And don't have any problems.
But thats not to say that a universal tower with more joints in it wouldn't have issues..... specifically joints in the top corners of the tower. As I understand it, if you frequently check how tight those joints are, you will be fine. But if you let it go at all, you run the risk of breaking things, especially if the tower is loaded heavy on one side. Which is possibly why they don't advise it.
(Message edited by bill_airjunky on May 06, 2009)