I have a retired Z-stand also - too big, heavy and takes too long to setup. I have had an X-stand collapse on stage and wreck two keyboards so those are no longer an option for me either. THE best stand IMHO is the QuikLok Monolith, which both Scott Yee and I enjoy using. It's light, folds flat and sets up instantly with no chance of collapse:
http://www.quiklok.com/search_list.taf?_function=detail&Layout_0_uid1=33262