Well, swing and a miss on the "Vivo Standing Desk Converter". Almost 3500 good reviews on Amazon, and it was a piece of ****. It had potential, but tolerance stack was its worst enemy. It uses plastic block sliders in lieu of actual bearings, inside some stamped/formed channels. There was so much play between the block and the channel, I could slide a credit card between them. At the top, the crossbar just rests inside a hole drilled in the sliders, and those had even more slop. So, 6 points of slop at a 9" extended height meant over 5/8" deflection at the keyboard tray, and the whole thing wobbled and clicked any time you even looked at it wrong.
I've ordered a z-frame "VertDesk" from BTOD which costs another $200, but is described as the "sturdiest they've tested to date", so fingers crossed.