I'm actually using the Amazon Ergotron generic https://www.amazon.com/gp/product/B00MIBN16O/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The trick is to tighten the spring (underside of the arm) and it'll hold things up just fine. The Cintiq weighs more than the Dell and holds pretty well as well. For the arms for the monitors on either side I"m using the Ergotron extension to get more reach.
The Amazon is such a perfect generic that Ergotron accessories fit on it perfectly.