I actually have a Quik Lok version of one of these. It has a 65lbs Kurzweil on the bottom and my 45lbs G70 on top (home use only, LOL!). Not a trace of bounce on the bottom, only the barest hint of bounce on the top with me pounding away... Highly recommended.
What keyboards are you planning on putting on the stand, Nick, other than the G70 on the bottom?