If you want to stop bounce altogether, try one of these
http://www.zzounds.com/item--QLKWS550

The legs are at the corners, so bounces never happen.

I still use an amazing single tier X-stand that the now defunct Invisible Stands made. Unlike all other X stands, the legs were not vertical, but angled away from you (and braced at both ends) so that, as you load it up with more weight, tension actually makes it stiffer and more stable!

I wish they were still in business.... these were amazing! (I also have one of their triple tier stands - a pig to set up, but very sturdy)

However..... you'll find a tempo that makes ANY X-stand bounce, just like marching over a bridge! If you want to eliminate the bounce altogether, try the Quiklok....

And no, it won't hurt your keyboard unless it falls off the stand! People complain about carrying heavier arrangers, but put them on a stand, and their mass makes them FAR harder to make bounce!