FWIW the cups will stay put. Never had a situation where the cup hanging off the back of the couch spun.
That said, placing the Empyrean on the couch takes a bit more time compared to the traditional T-Type stand- especially given the cost of the Empyreans. I am OCD about how the Empyrean sits on the couch, to the point where I have to make sure the front facing earcup is perfectly flat against the couch surface directly above the Meze logo. I also make sure the headband sits perfectly centered along the top edge of the couch on the "r" in Empyrean, evenly spaced from right and left edge.
Come to think about it, kinda like adjusting the position of a painting on a wall.